Meat Filling:

1. In a large bowl, combine beef, onion, scallion, ginger, soy sauce, sugar, salt and pepper. Mix together well. Place the meat filling in the refrigerator for at least one hour to marinate.

Pastry Dough:

1. Add flour, butter, sugar, and salt into a food processor. Pulse mix on and off for 1 minute until the mixture turns into smaller pieces of dough (similar to green peas).
2. Drizzle ice water into the mixture. Close the lid and pulse mix on and off for another minute; this time the flour mixture will turn into a bread crumbs consistency.
3. Lightly dust your work surface with flour. Place your crumby dough onto the work surface. Squeeze them all together and bring in all the loose crumbs until you form a nice and smooth dough. Shape the dough into a disc.
4. Wrap the disc in plastic wrap and refrigerate for 1 hour.

Assembling and Baking:

1. Preheat oven to 400 F.
2. Divide the dough into 8 pieces. Roll out each piece into a round circle approximately 5-inch in diameter, and 1/8-inch thick.
3. Put 1 and 1/2 tablespoons of meat filling at the centre of each circle. Bring the edges up, enclosing the filling and pleat the sides together into a little bag to seal the mixture inside (see photos above in post). Flip the pastry over and press down gently, using your hands, to shape it into a disc.
4. Place pastries on a parchment-lined cooking tray. Brush egg wash on top of each pastry and sprinkle black sesame seeds on top.
5. Bake for 28 minutes until golden and crisp.