Cut radish into round slices, cut into beveled edges, and boil in the water in which rice water.
When the radish is slightly softened, remove from heat and rinse the radish.
Drain dried shiitake mushrooms from water and set aside.
Reserve kombu(kelp) soup stock.
Combine the shiitake mushroom stock from 3 and soup stock from 4 to 300 ㏄, and seasonings (sake, soy sauce, white soy sauce, mirin, and love).
Add 2 to 5,shredded shiitake mushrooms and kelp, and simmer until tender.
If there is any broth left over from step 6, add potato starch to thicken the soup.
Serve 6 and pour 7 on top. (Please garnish with Japanese parsley and yuzu kosho if you like.)