Steamed Pork Buns

Name: Steamed Pork Buns
Cuisine: Asian, Chinese
Ingredients: 1 1/2 teaspoons instant dry yeast; 3/4 cup lukewarm water; 2 tablespoons canola oil; 2 tablespoons sugar; 2 teaspoons baking powder; 3 cups flour; 1 tablespoon sugar; 1 tablespoon soy sauce; 2 teaspoons oyster sauce; 1 tablespoon water; 2 teaspoons canola oil; salt and ground white pepper to taste; 2 scallions, chopped white and green parts; 1/2 pound char siu, diced; 1 tablespoon Shaoxing rice wine; 1 1/2 tablespoon cornstarch dissolved in 2 tablespoons water