Left Coast Sourdough: This loaf’s history dates to San Francisco and the California gold rush, when prospectors carried mixtures of flour and water in packets attached to their waists. The result was a fermented leavening agent and a chewy, tangy bread. Allegro’s liberal coast version is a traditional, long-fermented loaf which rises overnight in a banneton (coiled basket) for a distinctive patterned, thick crust and spongy, flavorful crumb.