Flaky char siu pastry filled with sweet barbecue pork is a dim sum classic. A protein-rich, family treat with buttery, fresh layers.
Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper.
In a mixing bowl, cut 6 tbsp of cold unsalted butter into the flour until pea-sized pieces form. Add milk and mix to form a soft dough, then chill in the fridge for 20 minutes.
To make the filling, heat 2 tbsp butter in a skillet over medium heat. Add diced char siu pork and sauté for 2 minutes. Stir in sugar, soy sauce, oyster sauce, and sesame oil; cook for another minute.
Mix cornstarch with 2 tbsp water to form a slurry, then add to the pork mixture. Stir and cook until thickened, about 1–2 minutes. Cool completely.
Roll out dough on a floured surface to ¼-inch thick. Cut into 6 rectangles. Place filling in the center of each, fold over, and seal edges tightly.
Place pastries seam side down on the prepared baking sheet. Beat egg and brush over tops for shine. Bake for 22–25 minutes until golden brown and flaky. Cool slightly before serving.