Prepare the oxtails – In a large bowl, cover the oxtails in cold water and mix in a tablespoon of sugar. Doing this will remove the blood and impurities from the oxtail. Let set for about 1-2 hours before draining.
Parboil the oxtail – After draining the water, fill the Instant pot with water and add in the oxtails. Turn the Instant Pot onto sauté mode and bring the water to a boil and let simmer for about 5 minutes until the water turns cloudy with debris rising to the surface. Turn off the pot and drain the water.
Cook in Instant Pot – Fill the instant pot with about 3 cups of water and add in the oxtail pieces. Cut the daikon into small slices. Add the daikon and whole garlic cloves into the Instant Pot. Close the Instant Pot and the pressure valve and let it cook on high pressure for 1 hour, and let it release naturally for about 15 minutes.
Serve – After the soup has been simmered to a milky broth-like complexion, add to a soup bowl and serve with sea salt, pepper, and scallions. Traditionally, the eater will season the broth to their taste. You can also serve it with a side of kimchi. Some people like to add in the kimchi juice to give it a slight kick.