• Before You Start…Please note that this recipe requires 2 hours of Soaking Time + Pressurizing/Depressurizing Time. 

  Gather all the ingredients.
  

To Prepare the Oxtails

• Trim and discard any excess fat attached to the oxtail pieces. To completely remove the blood and impurities from the oxtail bone, soak 2 lb oxtails in cold water for 1 hour, changing the water a few times.
  

To Prepare the Vegetables

• Meanwhile, cut 1 onion into wedges, chop 2 ribs celery into small pieces, and cut 2 carrots into chunks.
  
• Roughly cut ¼ head green cabbage into 1-inch (2.5-cm) squares and rinse under running water.
  
• Cut 2 tomatoes into wedges and cut the wedges in half crosswise. Peel and cut 2 Yukon gold potatoes into quarters and soak them in water for 15 minutes to remove the excess starch.
  
• Cut ½ lb boneless beef chuck roast (or stew beef) into smaller pieces. Pat the pieces dry with a paper towel for searing later.
  

To Boil the Oxtails

• After soaking the oxtails for one hour, drain the water. Place them in a large pot and cover with cold water. Bring it to a boil over medium-high heat. Once boiling, turn down the heat and simmer for 15 minutes. Using a fine-mesh sieve, skim off the foam and scum on the surface frequently. After simmering, take out the oxtail or drain the water. Blanching oxtails before cooking helps remove blood and impurities.
  

To Sauté the Ingredients

• Press the Sauté button on an Instant Pot (I use a 6 QT Instant Pot) or heat your stovetop pressure cooker. Add 1½ Tbsp extra virgin olive oil to the pot.
  
• Once the pot is hot, add the chuck roast (or stew beef) and season with ⅛ tsp Diamond Crystal kosher salt and ⅛ tsp freshly ground black pepper. Sear the beef until it‘s brown on all sides. For a good sear, don’t flip the pieces around until they release themselves. Transfer the meat to a plate.
  
• Add the onion and celery and sauté until they are coated with oil and become tender. While sautéing, scrape the flavorful charred bits from the bottom of the pot. Add the tomatoes, carrots, and cabbage and toss to coat them with oil.
  
• When the vegetables are a bit wilted and soft, add the boiled oxtail, browned stew beef, and 4 cups beef stock/broth.
  
• Now, add Seasonings A: 2 Tbsp tomato paste, 1 tsp paprika, 1 Tbsp dried basil, and 2 bay leaves.
  

To Pressure Cook

• Cover and lock the lid on the pressure cooker. Make sure the steam release handle points at Sealing and not Venting. For the Instant Pot, press the Keep Warm/Cancel button to stop the Sauté mode. Press the Meat/Stew button to switch to the pressure cooking mode. Press the Plus (+) button to set the cooking time to 45 minutes.
  
• For a stovetop pressure cooker, cook on high heat until high pressure is reached. Then, reduce the heat to low but maintain high pressure for about 45 minutes.
• When it is finished cooking, the Instant Pot will switch automatically to the “Keep Warm” mode. Let the pressure release naturally, about 15–20 minutes.
• After depressurizing, unlock the lid. Add the potatoes and Seasonings B: 3 Tbsp brown sugar, 2 Tbsp white wine vinegar, and 2 tsp Diamond Crystal kosher salt). Add ⅛ tsp freshly ground black pepper, if you‘d like.
  
• Cover and lock the lid again on the pressure cooker. Make sure the steam release handle points at Sealing. For the Instant Pot, press the Keep Warm/Cancel button and press the Manual button to switch to pressure cooking mode. Press the Minus (-) button to change the cooking time to 15 minutes.
  
• For a stovetop pressure cooker, cook on high heat until high pressure is reached. Then, reduce the heat to low but maintain high pressure for about 15 minutes.
• When it is finished cooking, the Instant Pot will switch automatically to the Keep Warm mode. Let the pressure release naturally, about 15–20 minutes. Unlock the lid and mix well.
  

To Remove Fat from the Soup (optional)

• After making the soup, refrigerate it for at least five hours or overnight. The fat will harden and float to the top, where you can skim it off with a spoon or skimmer. Another "hack" I saw online was to hold a stainless steel ladle filled with ice cubes over the soup to attract the grease. The ladle works like a magnet and you just keep wiping off solidified grease on the lade with paper towel.

To Serve

• To serve, ladle the soup into individual bowls and enjoy!
  

To Store

• You can keep the leftovers in an airtight container and store in the refrigerator for up to 4 days or in the freezer for a month.