FOR THE BUNS:
5 cups bread flour or all purpose flour, plus ⅓ cup
⅔ cup water
1⅓ cup milk, divided
⅓ cup sugar
1 teaspoon salt
4 teaspoons instant yeast
4 tablespoons melted butter
eggwash (1 egg, beaten with a tablespoon of milk)
1 tablespoon sesame seeds (optional)
FOR THE FILLING:
2 tablespoons oil
½ cup finely chopped shallots or red onion
2 tablespoons sugar
1 ½ tablespoons soy sauce
2 tablespoons oyster sauce
1 ½ tablespoon sesame oil
1 tablespoon dark soy sauce
¾ cup chicken stock
3 tablespoons flour
2 cups diced Chinese roast beef (cha siu)
In a medium saucepan, mix ⅓ cup flour with ⅔ cup water and ⅓ cup milk until the flour is dissolved. Put the pan over medium heat and stir constantly until the mixture resembles a thick paste, about 3-5 minutes. Set aside.
In a large mixing bowl, combine 5 cups of flour, sugar, salt, and yeast. Add the flour paste (tangzhong), 1 cup milk, 2 eggs, and melted butter. Stir together to form a soft dough, and knead (by hand or with the dough hook attachment of your mixer) for 15-20 minutes. Form the dough into a ball and place into a lightly greased bowl. Cover with a damp cloth, and let rise for 1 hour.
While that’s happening, make the meat filling. Heat 2 tablespoons oil in a wok over medium high heat. Add the onion and stir-fry for 2 minutes. Add the sugar, soy sauce, oyster sauce, sesame oil, and dark soy. Stir and cook until it starts to bubble up. Add the chicken stock and flour. Reduce the heat to medium low and cook, stirring, for a couple minutes until thickened. Remove from the heat and stir in the roast pork. Set aside to cool.
After it has risen, separate the dough into 16 equal pieces. Shape each piece into a small circle, where the center is slightly thicker than the edges. Fill each with meat filling, and crimp them closed, making sure they’re tightly sealed. Lay them out seam side down on baking sheets lined with parchment paper, and let rise for another hour. Preheat the oven to 400 degrees (200 degrees C)
Brush with egg wash, sprinkle with sesame seeds (if using). Put them in the oven and immediately turn the oven down from 400 degrees (about 200 degrees C) to 350 degrees (about 175 degrees). Bake for about 25 minutes, or until golden brown.