In a large mixing bowl, whisk together flour, sugar, salt, and active dry yeast. Gradually pour in warm milk, mixing until a rough dough forms. Let it rest for 10 minutes.

Transfer the dough onto a floured surface and knead for about 10 minutes until smooth and elastic. Form the dough into a ball.

Place the dough ball in a lightly oiled bowl, cover and let it rise in a warm area for about 1 hour until it doubles in size.

Punch down the dough, turn it onto a floured surface, divide into 10 equal pieces, and shape each piece into a smooth ball, then flatten into circles.

Cook your choice of filling in a skillet with soy sauce and sriracha for 5-7 minutes. Mix in shredded cabbage and carrots, then let cool slightly.

Fill each dough circle with about 2 tablespoons of filling, fold and pinch to seal, then steam in a bamboo steamer for about 15 minutes.