Stir the pork and 1 tsp of cornstarch together in a bowl. Add the bamboo shoots and set aside. Dissolve the remaining cornstarch in 1/2 cup of water and set aside. Combine chicken broth and 3 cups of water in a large saucepan and bring to a boil. Add the pork mixture and bamboo shoots. Bring back to a boil and add soy sauce, vinegar and pepper. Add cornstarch mixture and stir. Carefully add the tofu. Pour a stream of beaten egg into the hot soup while stirring constantly. Remove from heat and pour into soup bowls to serve. Garnish with scallions and sesame oil and serve hot. Season with salt to taste. Makes 6 servings.