A sponge – typically a mixture of flour, liquid and yeast – adds a deeper flavor and better texture to finished bread.
Add flour to the proofed yeast
To make a sponge, first proof the yeast in a large mixing bowl. Add the flour and any other ingredients called for in the recipe and stir with a wooden spoon until smooth.
Cover and let the sponge stand
Cover the bowl with plastic wrap and let stand for at least 3 hours at cool room temperature or up to overnight in the refrigerator, or according to your recipe.
Bring sponge to room temperature
When the sponge is ready it will have risen, be bubbly and have a slightly sour or fermented smell. If the sponge has been refrigerated, bring it to room temperature for 1 hour before finishing the dough.
Check on the sponge periodically during proofing. If it doesn’t look bubbly or smell sour, discard it and start again with fresh ingredients.