1. Put the steamed bread in a pot, cover it with cloth, and put it in a warm and humid place (in a shady place). After about a week, patches of yellow enzyme bacteria will grow. 2. Crush the steamed bread, add salt, mix with appropriate amount of water and stir well. 3. Put the basin in the sun for about two weeks to make the yellow noodle sauce. Note: Don't forget to stir the sauce in the basin up and down frequently.