Place pork bone in a large pot and add water and ginger. Bring to a boil, then simmer for 2 hours. Discard bone. Add wine, pepper, and salt. Give cornstarch mixture a stir, then add to soup while stirring. Bring soup to a boil and add beaten eggs. Quickly stir in one direction only. Remove soup from heat. Add green onion, ham, and oil. Serve hot.