1. Prepare mung bean filling for later use
2. Purple sweet potato with milk
3. Put in the flour baking powder
4. Prove the dough for one hour
5. Divide into several parts
6. Stuffing into bean buns
7. Proof again in the cold water pot for 10 minutes
8. Steam for about 15 minutes
9. Put it in the plate, noisy, soft and sweet
