Soak the tiger lily buds and tree ears separately in hot water until soft. Cut tiger lily buds in half and break tree ears into strips. Slice bean curd 1/4 inch thick, then into 2 inch long strips. Sprinkle 1/4 teaspoon salt on curd and set aside. Add salt and soy sauce into chicken broth and bring to a boil. Add pork or chicken.
When broth is boiling, add tiger lily and tree ears. Dry bean curd strips with a paper towel then add to the soup. Add bamboo shoots and sliced fresh mushrooms. Add pepper to make soup hot. Add vinegar to make soup sour. Bring slowly to a boil. Thicken soup with cornstarch mixture. When thick, remove from heat then pour beaten egg, stirring constantly. Stir in sesame oil and garnish with scallion.
