Baked Barbecued Pork Buns

FOR FILLING: In a small bowl, stir together the 3 sauces, water, cornstarch and sugar until smooth; set aside. Preheat a wok over medium heat and add the oil. When it is hot, add both onions and the ginger and stir-fry until the onions are softened but not browned, about 1 minute. Increase the heat to high, add the pork and toss to mix. Stir the sauce quickly and add to the pork. Bring to a boil and stir until thickened, about 30 seconds. Stir in the sesame oil. Transfer to a bowl, cover and refrigerate until well chilled.

FOR BREAD: In a bowl, stir together the yeast, 1 tablespoon of the sugar and the warm water. Let stand until the yeast bubbles, about 3 minutes. Stir in the warm milk, oil and egg; set aside. In a food processor fitted with the metal blade, combine the flour, salt and the remaining 2 tablespoons sugar. With the motor running, slowly pour in the yeast-milk mixture. Process until the dough forms a rough ball and begins to pull away from the sides of the work bowl, about 15 seconds. If it is sticky, sprinkle in a little flour and process for 30 seconds longer.

Turn out the dough onto a lightly floured work surface and knead until smooth and spongy but resilient, 3-5 minutes. Form into a ball, place in a bowl and cover with plastic wrap. Let rise until doubled in size, about 2 hours at warm room temperature (or overnight in the refrigerator).

Turn the dough out onto the work surface. Sprinkle with the baking powder and knead until incorporated, about 3 minutes. Cut the dough in half and roll each half into a rope 8 inches long. Cut each rope into 8 pieces. Cover unused pieces with a damp kitchen towel. Roll each piece into a ball. Using a rolling pin, flatten each ball into a round 5 inches in diameter. To fill each bun, place 2 tablespoons filling in the center of a round. Pull the edges so that they come together and then pinch them together securely to enclose the filling. Shape into a smooth domed bun and place, pinched side down, on a parchment square. Set on a baking sheet. Make the remaining buns in the same way and place 2 inches apart on the sheet. Cover with a kitchen towel and let rise in a warm place until doubled, about 30 minutes.

Preheat an oven to 350 degrees. To make the glaze, in a bowl, stir together all the ingredients.

Just before baking, brush the buns with the glaze. Bake until golden brown, about 25 minutes. Serve hot or at room temperature.