In a large mixing bowl, combine all-purpose flour, glutinous rice flour, baking powder, salt, and sugar. Gradually pour in warm water, mixing until a soft dough forms. Knead for 5-10 minutes until silky smooth, then cover and let rise for about an hour until doubled in size.

Once the dough has risen, punch it down and divide it into equal pieces. Roll each piece into a ball, then flatten it slightly. Add a generous spoonful of the spicy lamb mixture into the center, pinching the dough edges together to form a bun.

In a skillet over medium heat, sauté chopped onion until translucent. Add garlic and ginger, cooking for another minute.

Stir in ground lamb and spices, cooking until the meat is browned and fragrant.

Add diced tomatoes and fresh cilantro, cooking until the mixture thickens and melds. Set aside to cool slightly.

Prepare your steamer by lining the basket with parchment paper or cabbage leaves. Arrange the shaped buns inside, ensuring there's space for them to expand. Steam for about 15-20 minutes until fluffy and cooked through.

After steaming, allow the buns to cool slightly before serving. They're best enjoyed fresh, accompanied by your favorite dipping sauces.