Building a Leaven
A “leaven” is a combination of flour and water that has been inoculated with a portion of a sourdough starter. In our bakery, building a leaven to mix with was crucial to avoid putting stress on the starter by using and feeding it in mass quantities. A leaven essentially acts as a medium between the bacteria in your starter and your bread dough that allows you to use smaller amounts of starter to achieve the same result. The leaven will be built the night before you intend to mix, and two days or more before you intend to bake, so plan accordingly.