Blanch the seaweed, wood ears and bean curd for 30 seconds in a kettle of boiling water. Drain. Mix the pork loin with the first measure of soy sauce, quarter of the cornstarch and one third of the sesame oil. Heat the first measure of water, the salt and sugar to boiling in another kettle. Add the seaweed, wood ears and bean curd. Add the pork loin when the water returns to a boil. Place the second measure of soy sauce, vinegar, the remaining sesame oil, the pepper, coriander, scallions and ginger root in a bowl. Mix. Set aside. Dissolve the remaining cornstarch in the second measure of water. Add to the soup. Turn off the heat. Add the beaten egg to the soup in a thin stream, stirring all the while. Stir in the scallion mixture. Ladle the soup into bowls. Serve hot.