For a classic sourdough bread recipe, we used a mixture of bread flour and whole-wheat flour for complex flavor. For a classic sourdough bread recipe, we used a mixture of all-purpose flour and whole-wheat flour for complex flavor. Sifting the whole-wheat flour removed excess bran, ensuring a light and airy loaf. For convenience and deep sourdough flavor, we let the shaped loaf proof overnight in the refrigerator. Baking it in a covered Dutch oven trapped steam to provide a crisp, crackling crust.