2. Ingredients: old yeast head: 50g medium gluten flour, 50ml cold water, yeast1g; Steamed bread: 500g medium gluten flour, cold water 180ml, and 3g edible alkali.

3. Practice: Make old noodles: Mix 50g of gluten, 50ml of cold water and 1 g of yeast evenly, put them in a container with a lid, and cover them. At room temperature, the fermented old noodles will be sour and covered with round holes after standing for 12- 15 hours.

4. Making steamed bread: mix the old dough fermented the day before with 500g flour and180ml water to make dough. Do not put surface alkali at this time.

5, the first fermentation: fermentation until the dough becomes twice the size and slightly sour, rubbing with your fingers, the dough will not rebound, tear the dough, showing a honeycomb shape.

6. Knead the dough with alkali: After fermentation, sprinkle 3 grams of dry edible alkali on the dough and knead it into the dough bit by bit, as long as it is evenly kneaded. Making steamed bread: Take a kneaded dough and knead it into a round steamed bread.

7. Serving for the second time: After the dough is completely shaped, put it on the steamer for the second proofing. After 20-30 minutes, the steamed bread will become bigger, not twice as big. Steaming: first boil the water in the pot, then steam it in steamed bread 15 minutes.