Oxtail Soup Recipe (Slow Cooker or Instant Pot)

Ingredients Instant Pot Slow cooker Serving Storage Is it Peat approved? FAQ

This is the oxtail soup I make in the Instant Pot when the weather turns cold: grass-fed oxtail, potatoes, carrots, garlic, ginger and rosemary, cooked for 4 hours at high pressure until the meat falls off the bones. Ray Peat, asked which food source of collagen works best, answered, "I like oxtail soup."^[1] The recipe comes first, for the Instant Pot or a slow cooker, and after it I check each ingredient against what Peat said and wrote.

Key takeaways

• Instant Pot: 4 hours at high pressure with a natural release. Slow cooker or crock pot: 8 hours on low.
• One package of oxtail, about 2.5 lb (1.1 kg), makes about 4 bowls.
• Roasting the oxtails first adds flavor, but the soup is still good without it.
• Salt lightly at the start and adjust at the end.
• Oxtail, potatoes, salt and well-cooked mushrooms match Ray Peat's food positions. Fish sauce, coconut aminos and cooked carrots do not.

This recipe is for education and home cooking. I am a certified clinical herbalist, not a physician, and nothing here is a diagnosis or treatment for any condition. The Ray Peat section reports what he said and wrote. It is not medical advice, and his positions have not been tested in clinical trials. Do not start, stop or change a medication or a prescribed diet based on this article. Tolerance to foods varies from person to person, and anyone with a food allergy, including a fish allergy, should check every ingredient.

Oxtail soup ingredients

Evidence: kitchen practice. Quantities are what I use; adjust to taste.

• 1 package grass-fed, grass-finished oxtail, about 2.5 lb (1.1 kg). I find oxtail to not be that meaty, so often I'll use 2 packages for a meatier soup.
• 3 garlic cloves, crushed under the flat side of a knife and added whole
• Sea salt or another natural salt, about 1 teaspoon to start (I use Maldon or Crucial Four)
• Black pepper, about 1/2 teaspoon
• 2 bay leaves
• 3 carrots, peeled and chopped
• 3 potatoes, peeled and chopped
• 1 teaspoon dried rosemary, or 1 fresh sprig
• 1 thumb-sized piece of ginger, cut thinly in long pieces so they are easy to remove
• 2 tablespoons coconut aminos, to boost flavor
• 2 teaspoons fish sauce (optional)
• Optional: a small handful of dried mushrooms, or 8 oz (225 g) fresh white button mushrooms
• Filtered water to cover, added last

I try to get grass-fed, grass-finished oxtail from a local farm. Luckily I live in Montana, where there are tons of options. If you don't have anything local, I like White Oak Pastures. They ship frozen and have great quality beef. I bought from them before moving to Montana and was never disappointed.

The fish sauce is optional, but it gives next level flavor. Leave it out if you are allergic to anchovy, but the soup will be less tasty.

You can use unsalted broth or stock instead of water. If yours is salted, leave out the salt at the start and adjust to taste at the end of cooking.

Optional: roast the oxtails first

Roasting the oxtails in the oven before they go in the pot adds flavor. Spread them on a sheet pan and roast at 400°F (205°C) for 30 minutes, turning them once. Sometimes I am short on time and skip this step, and the soup is still super good.

How to make oxtail soup in the Instant Pot

Evidence: kitchen practice. This is my usual method.

1. Put the oxtails in a 6-quart or 8-quart Instant Pot.
2. Add the garlic, ginger, bay leaves, rosemary, salt and pepper, then the carrots, potatoes and mushrooms if you are using them.
3. Pour in the coconut aminos and the fish sauce.
4. Add filtered water last, enough to cover everything, and stay below the pot's max fill line.
5. Lock the lid, set the valve to sealing, and pressure cook on high for 4 hours. On my Instant Pot Pro, I select Pressure Cook, then scroll to the Beef setting and run it at 4:00 on high pressure. The factory default for that setting is 30 minutes, so check that the display reads 4:00 before you start.
6. Let the pressure release naturally, which takes about 25 minutes with a full pot. A quick release with this much liquid will spit hot broth through the valve.
7. Remove the bay leaves, ginger and rosemary sprig. The garlic can come out too, but sometimes I leave it in.
8. Taste the broth and adjust the salt.

I cook it for 4 hours, and at that point it seems just barely done to the level I expect: it tastes like pot roast, and the meat falls off the bone with gentle pulling. I think anything less than 3 hours in the Instant Pot would not be tender enough, and you would have trouble getting the meat off the bones.

The meat and potatoes take up salt as they cook, so the broth tastes less salty at the end than it did at the start, and I adjust the salt after cooking for that reason. If you accidentally oversalt, you can add a potato to soak some of it up.

Some people tie the bay leaves, ginger, rosemary and garlic in a piece of cheesecloth so they come out in one bundle. I don't normally do this, but it makes finishing and serving a little faster.

How to make oxtail soup in a slow cooker or crock pot

Evidence: kitchen practice. Same ingredients, longer cook.

1. Put everything in the slow cooker or crock pot in the same order as the Instant Pot method, with the water added last to cover.
2. Cook on low, covered with a lid for 8 hours, or until the meat pulls away from the bones.
3. Remove the bay leaves, ginger and rosemary.
4. Adjust the salt to taste before serving.

How I serve oxtail soup

Evidence: kitchen practice.

I serve this oxtail soup with either potatoes or rice. When plating, I like to pre-remove the vertebrae bones so the soup is easier to eat. Often you'll get a few bones that have soft marrow inside. I like to gently poke out with a chopstick so that I don't miss out on those nutrients.

For more gelatin-rich cuts, see my osso bucco recipe, my savory beef and gelatin broth bowl and my Instant Pot chicken bone broth.

Cooling and storage

Evidence: standard food-handling practice.

Cool the soup and refrigerate it within 2 hours. It keeps for 4 days in the fridge and 3 months in the freezer. Chilled oxtail soup usually sets into a gel with a layer of fat on top. The gel melts back into oxtail broth when the soup is reheated, and the fat can be lifted off or stirred back in.

Handmade in Montana

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Is this oxtail soup Ray Peat approved?

Evidence: Ray Peat's articles and recorded interviews, cited by number. These are his positions, and no trial has tested this soup.

Most of the ingredients in this pot match what Peat said about food. Three do not fully match his ideals: the fish sauce, the coconut aminos and the cooked carrots. My 4-hour cook is the other somewhat grey area, and it is covered at the end of this section.

Oxtail

Asked in a 2021 radio interview which food source of collagen works best, Peat answered, "I like oxtail soup," and gave the gelatin in the ligaments and tendons as the reason.^[1] In 2011 he said that when he was not using powdered gelatin, "mostly I make oxtail soup or lamb shank soup."^[2] His essay on gelatin argues that muscle meat eaten alone supplies too much tryptophan and cysteine, and that gelatin, which is about 35% glycine, balances those amino acids when it is eaten at the same meal.^[3] Oxtail brings the meat and the gelatin in one cut, which I cover in more detail in foods high in collagen.

He also preferred tail and joint cuts to marrow bones for broth. In a 2014 interview he said marrow bones are high in iron and that "the tail is all joints and so that's very good."^[4] On beef in general he wrote, "Grass-fed organic beef fresh from a local farm would be a reasonable choice."^[5]

Potatoes and rice

Peat grouped roots and tubers with fruit as foods that provide "a high concentration of nutrients along with low concentrations of toxic antimetabolic substances."^[6] Asked whether cooked potatoes are good food, he said, "Yeah, very good."^[4] In 2022 he added that a potato should be well cooked, with the starch reaching about 211°F (99°C), and eaten with butter or cream.^[7] Four hours under pressure cooks the potatoes well past that point, and they are eaten in a broth that carries the fat from the oxtail.

On rice, he said polished white rice has most of the oil of the bran and germ removed, which makes it "less allergenic" than unpolished rice.^[7] Starch was still not his first choice: "when better foods are available they should be used instead of starches."^[8] This soup can also be made without rice or potatoes.

Mushrooms

Peat said of mushrooms that "if they taste good and they're well cooked, I think they're all going to have some benefits."^[9] Asked whether white button mushrooms can be pressure cooked, he said the cooker's pressure release vents what cooks off, and that the kitchen should be ventilated while cooking.^[10] Asked in another interview whether cooking mushrooms for three hours gets rid of their agaritine, he said it is either turned into something different or vaporizes.^[11] My white button mushroom article has more on why he favored them.

Carrots

Peat's daily carrot was raw. In 2011 he said, "From a cooked carrot, you absorb almost all of the carotene, and the carotene has an antithyroid action," and added that more potassium, calcium and magnesium come out of the cooked carrot.^[12] Three carrots divided across a pot is a small amount per bowl, and they can be left out. The version he recommended is in my raw carrot salad article.

Garlic, ginger, black pepper and herbs

On garlic, Peat said, "as just foods, garlic and onions are fine." His caution was for people who are allergic to them, and for low-thyroid people, who he said often get gallbladder spasms from cooked garlic and onion.^[2] Of spices in general he said that "so many of them are allergens,"^[2] and that "they all have their toxic levels." In the same answer he called clove "a pretty safe spice" and went on to list cinnamon and black pepper.^[13] Asked about garlic and ginger used against gut bacteria, he said, "They have their own allergens, so you have to be careful."^[14] I have found no comment from him on rosemary or bay leaf.

Fish sauce and coconut aminos

Transparently, fish sauce is the least Peat-friendly ingredient in this pot. I use Red Boat, a Vietnamese fish sauce with two ingredients, anchovies and sea salt. The label lists 0 g of fat, so the fish oil is not the issue here. Fish sauce is a concentrated source of glutamate: in a study of Vietnamese anchovy fish sauce fermentation, glutamic acid was the most abundant amino acid in the broth after 6 months, at about 23 g per kg, a total that includes glutamate still bound in peptides.^[15] An analysis of Italian anchovy sauce, a related product made from gutted anchovies, also found glutamate to be the dominant free amino acid, and reported that part of the aroma comes from aldehydes formed when the unsaturated fats in the fish oxidize during fermentation.^[16]

I have found no comment from Peat on fish sauce itself, but three of his statements come close. Asked whether tamari, as a fermented soy sauce that forms a natural MSG, should be limited, he answered, "I think so."^[17] On soy sauce he said, "I think it's safe to use occasionally in a small amount."^[18] In his salt article he wrote that several studies show dried fish and pickled vegetables are carcinogenic, "probably because of the oxidized fats, and other chemical changes, and fungal contamination."^[19]

Coconut aminos is soy-free, but it is another aged, savory sauce, and I have found no comment from Peat on it. I use 2 teaspoons of fish sauce and 2 tablespoons of coconut aminos in a whole pot for flavor. Both can be left out, but the soup will be less tasty without them.

Cook time and the Instant Pot

Oxtail needs a long cook, because the collagen in the tendons and cartilage has to break down into gelatin before the meat comes off the bones. In my Instant Pot that takes 4 hours at high pressure. I have found no cooking time from Peat for oxtail, but he made the soup himself,^[2] and he said a proper broth made from joints and cartilage "should be rubbery" once it is cooled.^[20]

His comments in favor of quick cooking used salmon and steak as the examples. In 2019 he said of meat and fish, "If it's overcooked, the cholesterol is progressively oxidized," and that a slow-cooked steak tastes bad because the "fats and cholesterol have been seriously oxidized."^[21] Asked in 2021 about cooking meat in pressure cookers, he said, "It doesn't generally taste very good," and then, "Quick cooking at normal pressure, I think is the best for taste and health."^[22] On the optional roasting step, he said that browned meat forms some of the same compounds that form when starches brown.^[23]

Start here The Ray Peat Diet Guide Every food he mentioned, his hormone framework in order, and links to his interview audio transcripts, and articles. Open the guide →

Frequently asked questions

Evidence: kitchen practice unless a source is cited.

What is oxtail?

Oxtail is the tail of beef cattle, cut into short sections. Each piece is a tail bone surrounded by a ring of meat, with a lot of tendon and cartilage. Oxtail soup is also called beef tail soup or cow tail soup.

How long does oxtail take to cook?

In the Instant Pot, I pressure cook my oxtail soup on high for 4 hours, then let the pressure release naturally, which takes about 25 minutes. In a slow cooker or crock pot, it cooks on low for 8 hours, or until the meat pulls away from the bones. At 4 hours under pressure the meat tastes like pot roast and falls off the bone with gentle pulling. I think anything less than 3 hours in the Instant Pot would not be tender enough.

Do I have to brown oxtail before making soup?

No. Roasting the oxtails at 400°F (205°C) for 30 minutes adds flavor, but the soup is still good without it.

Can I make oxtail soup in a slow cooker or crock pot?

Yes. Use the same ingredients and cook on low for 8 hours, or until the meat pulls away from the bones.

Is oxtail good for bone broth?

Oxtail makes a broth that sets into a gel when chilled, because the tail is mostly joints, tendon and cartilage. Ray Peat preferred tail and joint cuts to marrow bones for broth.^[4] For a plain oxtail bone broth, strain the liquid after cooking.

Why did my oxtail soup turn to jelly in the fridge?

Oxtail is mostly joints, and the collagen in the tendons and cartilage cooks into gelatin, which sets when cold. It melts back into broth when the soup is reheated.

Can I leave out the fish sauce?

Yes. The soup will be less tasty without it. Leave it out if you are allergic to anchovy.

Where can I buy grass-fed oxtail?

A local farm is my first choice. If you don't have one nearby, White Oak Pastures ships frozen grass-fed beef.

Did Ray Peat eat oxtail soup?

Yes. He said, "I like oxtail soup," when asked for the best food source of collagen, and in an earlier interview he said he mostly made oxtail soup or lamb shank soup.^[1][2] My Ray Peat diet guide lists the other foods he discussed.

Sources

Interview quotes come from the transcripts in the Ray Peat Archive, which are machine-generated from the audio. Ray Peat was an independent physiologist; his articles and interviews are not peer-reviewed studies.

1. Peat R. Interview with Patrick Timpone. One Radio Network. October 18, 2021.
2. Peat R. Interview with Josh Rubin, "Q and A 1." East West Healing radio. July 12, 2011.
3. Peat R. "Gelatin, stress, longevity." raypeat.com. https://raypeat.com/articles/articles/gelatin.shtml
4. Peat R. Interview with Patrick Timpone, parts one and two. One Radio Network. January 1, 2014.
5. Peat R. "Meat physiology, stress, and degenerative physiology." raypeat.com. https://raypeat.com/articles/articles/meat-physiology-stress.shtml
6. Peat R. "Vegetables, etc. Who defines food?" raypeat.com. https://raypeat.com/articles/articles/vegetables.shtml
7. Peat R. Interview with Patrick Timpone. One Radio Network. January 17, 2022.
8. Peat R. "Glycemia, starch, and sugar in context." raypeat.com. https://raypeat.com/articles/articles/glycemia.shtml
9. Peat R. Interview with Patrick Timpone. One Radio Network. February 21, 2022.
10. Peat R. Interview with Patrick Timpone. One Radio Network. May 16, 2022.
11. Peat R. Interview with Danny Roddy and Georgi Dinkov, "#51: Heat Shock Proteins, Antibiotic Resistance, DHT Safety, Energy and Aging." YouTube. https://www.youtube.com/watch?v=5sop_zLMZ34
12. Peat R. Interview with Josh Rubin, "Serotonin and Endotoxin." East West Healing radio. August 25, 2011.
13. Peat R. Interview with Patrick Timpone. One Radio Network. December 17, 2019.
14. Peat R. Interview with Patrick Timpone. One Radio Network. May 21, 2019.
15. Nguyen ADQ, Sekar A, Kim M, et al. "Fish sauce fermentation using Marinococcus halotolerans SPQ isolate as a starter culture." Food Science & Nutrition. 2021;9(2):651-661. https://doi.org/10.1002/fsn3.2024. Three of the authors work in research and development at Masan Industrial, a Vietnamese fish sauce maker, and the others are at the University of Suwon; the authors declare no conflicts of interest. The figure cited is from the control broth, without the starter culture.
16. Corona O, Cinquanta L, Li Citra C, et al. "Evolution of free amino acids, histamine and volatile compounds in the Italian anchovies sauce at different ripening times." Foods. 2022;12(1):126. https://doi.org/10.3390/foods12010126. Authors are at Italian public universities and a public veterinary institute; the sauce samples came from a commercial producer, Rossi s.n.c.
17. Peat R. Interview with Andrew Murray and Sarah Johannesen Murray. Ask Your Herb Doctor, KMUD. January 21, 2022.
18. Peat R. Interview with Patrick Timpone. One Radio Network. March 16, 2020.
19. Peat R. "Salt, energy, metabolic rate, and longevity." raypeat.com. https://raypeat.com/articles/articles/salt.shtml
20. Peat R. Interview with Patrick Timpone. One Radio Network. October 19, 2020.
21. Peat R. Interview with Patrick Timpone. One Radio Network. August 20, 2019.
22. Peat R. Interview with Patrick Timpone. One Radio Network. January 18, 2021.
23. Peat R. Interview with Andrew Murray and Sarah Johannesen Murray, "Food." Ask Your Herb Doctor, KMUD. December 16, 2016.