Slow-cooker Hawaiian oxtail soup is thin, light, and deeply nourishing: oxtail simmered for twelve hours with orange peel, star anise, garlic, ginger, and cashews until the bones give up their collagen. The overnight chill lifts away the excess fat, leaving a clean, gelatinous broth that's kind to the digestion. Finished with tender mustard greens and chili flakes, with pho-style toppings at the table.
SERVES 6 TO 8
Oxtail is a tough but flavorful cut of meat that becomes very tender when cooked slowly. This Hawaiian version of oxtail soup is thin and light. The toppings are reminiscent of a Vietnamese pho. Traditionally this soup calls for peanuts but due to their creamy nature, cashews are a perfect Paleo substitute.
Oxtail bones have a lot of collagen, which makes for a gelatinous stock. Gelatin has many benefits, including improving digestion and soothing the GI tract.
INGREDIENTS
3 lbs/1 kg oxtail
1 strip orange peel (zest, not the pith)
4 cloves garlic
3 star anise
2-inch/5-cm piece of fresh ginger, peeled
1 tbsp/15 g sea salt
½ cup/85 g cashews
filtered water
1 tbsp/15 ml apple cider vinegar
1 bunch mustard greens
¼ tsp chili pepper flakes
FOR GARNISH:
coconut aminos
fresh cilantro
scallions, chopped
fresh ginger, grated
COOKING INSTRUCTIONS
Place oxtail, orange peel, garlic cloves, star anise, ginger, salt and cashews in a slow cooker. Cover with filtered water. Add 1 tablespoon/15 ml of apple cider vinegar. Cook on low for 10 to 12 hours. Allow the soup to cool. Move to a stockpot with a lid and chill in the refrigerator overnight.
By the next day, the fat will have solidified. Pull the fat off the oxtail and remove the star anise, orange peel and ginger. Bring the soup to a simmer. Add the mustard greens and the chili pepper flakes. Cook for 7 to 10 minutes or until mustard greens are tender. The meat can either be stripped from the bones before serving or the oxtails can be served bone in. Serve with coconut aminos, fresh cilantro, chopped green onions and freshly grated ginger for garnish.
CHEF’S TIP
For best results, trim oxtail of any excess fat. Better yet, ask your butcher to trim it for you!
Pro Tips
- Ask your butcher to trim the oxtail of excess fat — it saves you skimming work later and gives the cleanest broth.
- Use only the orange zest, never the pith; the pith's bitterness intensifies over the twelve-hour cook and will taint the whole pot.
- The overnight chill is functional, not just convenient — solidified fat lifts off in one sheet, and the broth improves immeasurably.
- Cashews stand in for the traditional peanuts and add a subtle creaminess to the long-simmered broth.
- Add the mustard greens at the very end so they wilt tender-crisp; overcooked greens turn the light broth muddy.
Frequently Asked Questions
Why cook oxtail soup for 10 to 12 hours?
Oxtail is a tough, collagen-rich cut. The long slow cook melts the connective tissue into the broth, creating the gelatinous stock this soup is famous for — great for digestion and gut health.
What garnishes should I serve with it?
Coconut aminos, fresh cilantro, chopped scallions, and freshly grated ginger — the pho-style toppings that let each bowl be seasoned to taste.
Can I use a regular stockpot instead of a slow cooker?
Yes — a very gentle stovetop simmer for 4 to 5 hours works, or a 300°F oven braise. The slow cooker is simply the most foolproof way to hold that low heat.
How do I store the soup?
Refrigerate up to five days or freeze for three months. The gelatin-rich broth will set solid when cold — that's exactly right.
Recipe Card
Ingredients
Method
- COOKING INSTRUCTIONS Place oxtail, orange peel, garlic cloves, star anise, ginger, salt and cashews in a slow cooker.
- Cover with filtered water.
- Add 1 tablespoon/15 ml of apple cider vinegar.
- Cook on low for 10 to 12 hours. Allow the soup to cool. Move to a stockpot with a lid and chill in the refrigerator overnight. By the next day, the fat will have solidified. Pull the fat off the oxtail and remove the star anise, orange peel and ginger.
- Bring the soup to a simmer.
- Add the mustard greens and the chili pepper flakes.
- Cook for 7 to 10 minutes or until mustard greens are tender. The meat can either be stripped from the bones before serving or the oxtails can be served bone in.
- Serve with coconut aminos, fresh cilantro, chopped green onions and freshly grated ginger for garnish. CHEF’S TIP For best results, trim oxtail of any excess fat. Better yet, ask your butcher to trim it for you!
