Heat a wok to high. Add the onion, garlic, ginger, and sesame seeds, and saute until soft and starting to brown. Add splash of vegetable stock or water if starts to stick.
Combine vegetable stock, Worcestershire sauce, soy sauce, kombu, and chili flake and add to cooked onion mixture. Stir well to release any pieces stuck to the bottom of the wok. Bring to a boil and simmer about 15 minutes to bring out the flavors of the kombu.
Add kimchi and stir. Let simmer a few minutes to heat through.
Add silken tofu and gently stir. You want large bite-sized chunks, so stir gently as not to break it down completely. Let simmer a few minutes to heat through.