2. Take the yeast according to the ratio of flour to yeast of 200: 1, put the yeast into a small bowl and stir it evenly with warm water;

3. Dig a hole in the middle of the noodles and pour in yeast water. Mix yeast water and flour with chopsticks;

4. Prepare warm water, then pour it into the dug hole and knead the noodles into floccules with chopsticks;

5. Knead the flocculent noodles together by hand, and then knead them hard after feeling soft. Knead into a ball;

6. Cover the surface with gauze and leave it in a warm place for about an hour. You can open the middle to see if there is a honeycomb in the middle of the flour. If it is, it means that the flour is fermented.