Cube lamb meat into 1/4“ (1-cm) pieces and add them into a large bowl. Add salt, cumin powder, black pepper. Mix well. Add onion and peanut oil, and mix again.

Add flour and salt to a large bowl. Stir to mix well. Add the oil and egg. Use a pair of chopsticks to whisk the flour until the wet ingredients are fully absorbed. Slowly add water onto dried flour and keep stirring, until soft dough flakes form and there’s no dry flour on the bowl. If there’s still too much dry flour left in the bowl, add a bit more water. If the dough flakes are very sticky to the touch, add more flour.

Dust both hands with dry flour and start gathering the dough flakes, until dough forms. Dust a working surface with flour and transfer the dough onto it. Knead the dough until the surface turns smooth, 5 to 10 minutes. The dough should be soft but should not stick to your hand.

Transfer the dough to a large bowl. Cover with a damp dish towel or plastic wrap. Allow to rest at room temperature for 15 minutes.

Knead the dough again until it’s very smooth, 2 to 3 minutes. Let rest for another 30 minutes.

Preheat the oven to 450°F (230°C). Line a baking tray with parchment paper.

Beat 1 egg yolk with the milk to make the egg wash. Reserve the white in another bowl.

Dust the working surface with flour again and transfer the dough onto it (try not to add too much dry flour as long as the dough doesn’t stick to the surface too much, so it’s easier to seal later). Divide the dough into two even pieces. Roll the dough into a long log. Divide each dough log into 5 equal pieces, so you get a total of 10 dough balls (mine weighs 48g to 50g per dough). Work on one at a time, using plastic wrap to cover the rest to prevent it from drying out.

Knead a piece of dough a few times to shape a ball. Press it into a round disc. Roll the dough with a rolling pin into a round disc that is slightly thicker in the center and thin on the edges, about 7” (18cm) x5” (13cm) in diameter.

Pack 4 to 5 tablespoons of filling into the center of the dough disc. Fold the longer edges of the dough and pinch them together. To help with sealing, you can brush some egg white until both short ends of the wrapper. Fold the shorter ends so the dough seals the filling inside. Press gently and place onto the baking sheet. Work on the rest of the dough in the same way.

Brush each bun with a thin layer of egg wash on top and sprinkle sesame seeds to garnish.

Bake on the middle rack for 25 minutes, until the surface turns golden brown. Let the buns cool off for 5 to 10 minutes before serving.