Heat oven to 375°F. In a wok or large skillet, heat oil over medium heat. Add onion and garlic; stir-fry until onion is soft. Remove from heat; add oyster sauce, soy sauce, sherry, cornstarch and sugar, stirring well to combine. Add pork and mix well.Divide bread dough into 16 pieces and form each piece into a 2-inch ball. Flatten balls into 3-inch rounds. Place about 2 tablespoons pork filling in the center of each round. Gather dough up and around filling by pleating along the edges. Place buns, sealed side down, on a nonstick baking sheet. Bake 25-30 minutes or until buns are browned.