Place the dried shiitake mushrooms in a bowl, cover them with water, and leave to soak for 30 minutes. Remove the mushrooms from the soaking liquid, (reserve the liquid for later use), trim the stems from the mushrooms, and thinly slice them. In a wok or large pot, heat the oil, and when hot add the ginger and garlic, and stir-fry for 1 minute. Add the Chinese cabbage, shiitake mushrooms, and shallots, and stir-fry for 3 additional minutes. Add the red pepper and bean sprouts and stir-fry for 2 minutes. Add the reserved mushroom soaking liquid, vegetable stock, tamari, mirin, and toasted sesame oil, and bring to a boil. Allow the soup to boil for 5 minutes, stir in the green onions, and serve immediately.

Serves 6-8