• Gather all the ingredients.
  
• In a bowl, soak 2½ lb oxtails in water for 1–2 hours. Change the water every half hour. This step will help remove the blood from the oxtails.
  

To Blanch the Oxtails

• Drain the water and transfer the oxtails to the inner pot of an Instant Pot.
  
• Add 6 cups water (or just enough to cover the oxtails). In the next step, you will bring the water to a boil on the Sauté mode. The Instant Pot manual says not to cover when using the Sauté mode, but I use a glass lid from another pot (so I can see inside) and keep it covered until boiling. The lid is optional but it helps to speed up the boiling.
  
• Press the Sauté button on your Instant Pot. Once boiling, remove the lid and cook for another 5–10 minutes.
  
• Press the Keep Warm/Cancel button on the Instant Pot to stop the Sauté mode. Drain the water and rinse the oxtails under running cold water. Set aside and clean the inner pot.
  

To Cook the Broth

• Cut 1 Tokyo negi (naga negi; long green onion) to separate the green and white parts. We only use the green part for cooking the oxtail. Slice 1½ knobs ginger with the skin on and smash 1 clove garlic.
  
• In the cleaned inner pot, put the oxtail, green part of the negi (or green onion), ginger, and garlic.
  
• Pour 8 cups water and add 1 tsp Diamond Crystal kosher salt. Make sure the oxtail is fully submerged. If you use more than 2½ lb oxtail, make sure that the water level does not exceed two-thirds the capacity of the pressure cooker.
  
• Cover and lock the lid on the pressure cooker. Make sure the steam release handle points at Sealing and not Venting. Press the Manual button to switch to High pressure cooking mode. Press the Plus (+) button to change the cooking time to 60 minutes.
  
• If you’re using a stove-top pressure cooker, you won’t have any buttons to press. Just cook on high heat until high pressure is reached. Then, reduce the heat to low but maintain high pressure for about 60 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 de-pressurizing is completed, unlock the lid. Set a fine-mesh sieve over a large bowl and strain the broth. Discard the aromatics and add the meat back into the broth.
  

To Serve Now

• You can’t get rid of as much fat, but skim it off the surface the best you can. Use the broth and meat for the recipe you’re cooking. Otherwise, season the broth with salt (the right good amount of salt is important for taste). Serve the soup and meat in a bowl topped with chopped green onion.
  

To Serve Later (Store Overnight)

• Cover and let cool completely. Store in the refrigerator overnight (or at least 4 hours until the fat solidifies). Once the fat is solidified on the surface, remove the layer of fat. You can use it for other recipes or discard.
  
• Transfer the oxtail broth to a pot (or back to the Instant Pot) and reheat.
  
• Use it for the recipe you’re cooking like Oxtail Oden (Fish Cake Stew) or Oxtail Udon Soup. Season accordingly. Or, you can season it with salt (the right amount of salt is important for taste), and serve the soup with the meat and chopped green onion or your choice of herbs.
  

To Store

• You can store the broth in the refrigerator for up to 3 days and in the freezer for up to 3 months.