This is a traditional Korean soup that can be made with a variety of ingredients but relies on Kim Chi and Radish for its basic flavor. It calls for a few specialized ingredients — they can all be found at most natural foods retailers now but also in specialty Asian food stores.
Make the broth: Heat 4 C. water in a pot. Add 3-4 dried shitake or other wild mushrooms, the washed leaves from 1 Trimmed Leek, 1 C. thinly sliced Watermelon or purple Daikon radish, and 1 square of dried kelp. Bring to a boil and simmer for one hour, then season with fish sauce or soy sauce. Strain out the kelp and the leek leaves.
Clean the trimmed leek and cut into julienne strips 1 inch long to make 1 C.
Soak and drain Spinach or Chard leaves to make 2 C. of packed leaves. Chop into ribbons.
Heat 1/2 t. Korean hot pepper flakes (gochugaru) in 1 T. vegetable oil in a heavy bottom pot. Add 4 minced cloves of garlic and the leeks. Cook for 2 minutes, then add 1/4 C. cabbage Kimchi along with 2 t. each Korean bean paste (dwengang) and chili paste (gochujang).
Add the stock and bring to a boil, then simmer. Add 1 C. diced sweet potatoes and 12 oz. silken tofu and use a spoon to break the tofu into bite-sized pieces. Simmer vigorously for 15 minutes.
Add 1 C. fresh mushrooms (traditionally Enoki, but can be just about any type) and the Spinach or Chard. Simmer for another 2-3 minutes.