01 - Combine ground pork, onion, garlic, soy sauce, oyster sauce, sugar, black pepper, salt, cornstarch, and sesame oil in a mixing bowl. Mix thoroughly until all ingredients are well incorporated and the mixture becomes sticky.
02 - Preheat oven to 400°F. Line a baking tray with parchment paper and set aside.
03 - On a lightly floured surface, roll out puff pastry sheets to about 1/8 inch thickness. Cut into 10 circles approximately 3.5 inches in diameter using a pastry cutter or round cookie cutter.
04 - Place 2 tablespoons of meat filling in the center of 5 pastry circles, leaving about 1/2 inch border around the edges.
05 - Brush the edge of each filled circle lightly with beaten egg. Cover with a second pastry circle and press the edges firmly to seal. Crimp edges with a fork to create a decorative pattern and ensure tight closure.
06 - Brush the tops of each pastry with remaining beaten egg to achieve a golden, glossy finish when baked.
07 - Transfer pastries to the prepared baking tray, spacing them about 2 inches apart to allow for expansion during baking.
08 - Bake for 20 to 25 minutes, or until pastries are puffed, golden brown, and the filling is completely cooked through.
09 - Let pastries cool on the baking tray for 5 minutes before transferring to a wire rack. Serve warm while the pastry remains flaky and crisp.