1Soak beef short ribs in cold water for two hours to get rid of any blood.
2Strain beef, add it to a pot, and cover with water. Bring to a boil and cook for 5 minutes to get rid of any scum.
3Strain the beef and rinse under cold water.
4Add back the beef to a pot with radish, onion, white portion of scallions, ginger, garlic, black peppercorns, and mirin. Cover with water and simmer on low for 3-4 hours.
5Halfway through, remove the radish and slice it into bite-sized pieces.
6Discard the aromatics and set aside the beef.
7Strain the broth and season with soup soy sauce, fish sauce, and salt.
8Soak sweet potato noodles in warm water for 10 minutes. Add soaked noodles to a pot along with the sliced radish, beef, and some broth. Bring to a boil and cook for 3-5 minutes.
9Serve with scallions, course salt, pepper, radish kimchi, and rice.