Put the 2 cups dashi stock and 1 cup braising liquid from buta kakuni in a pot and simmer. Taste the soup and adjust the seasoning with salt.
2 cups dashi stock, 1 cup braising liquid from buta kakuni, salt
Bring a large pot of water to a boil. Following the package instructions, boil the 200 grams udon noodles until about 1 minute before they are done. For example, if the directions say to cook for 6 minutes, boil them for 5. This is because the noodles continue to cook once you add them to the soup.
200 grams udon noodles
Drain the udon and give it a quick rinse to get rid of any extra starch. Put the noodles in 2 bowls, top with 8 slices buta kakuni (4 on each bowl), scatter some slices of 1 scallion on top, then ladle the hot soup over everything.