Slice listed ingredients into thin strips. Soak silken tofu in salt water to prevent breaking during cooking.
In boiling water add all ingredients listed except tofu. Simmer on low heat. Season with salt, mushroom seasoning, sugar, rice vinegar, black vinegar, and white pepper to taste. Thicken the broth by slowly adding potato starch premixed in water. Add silken tofu. Bring to boil. Season with sesame oil. Serve.