Xinjiang baked buns

Ingredients

• Dough: 300 g flour, 150 ml warm water, 5 g salt, 2 tbsp oil
• Filling: 300 g minced lamb (with some fat)
• Filling: 200 g onion (finely diced)
• Filling: 1 tsp salt, 1 tsp cumin powder, 1 tsp black pepper
• 1 tbsp sesame seeds
• 1 egg yolk (for egg wash)