In the sponge mixing method:
◦ a piece of dough saved from a previous batch is added to a new batch of dough before fermenting.
◦ dough is mixed in two stages: first yeast, liquid and half of the flour are combined; then, after the mixture rises, more flour is added to make the dough.
◦ all of the ingredients are combined and mixed into dough before fermenting.
◦ a natural sourdough starter is added to more flour and water to form dough, which is then fermented.