Bake yourself a magnificent-looking boule with a little help from a homemade sourdough starter. Since sourdough uses wild yeasts instead of commerically produced yeast to leaven, the final flavor of the bread can vary from tangy to nutty and sweet.
"Levain" is the French word for sourdough and in this recipe, it is the first step taken to make sourdough bread: A specific amount of starter, flour, and water is mixed together, left to ferment overnight, then used completely in the baking process. To ensure your starter is ready to bake with, always feed it a day before you plan to mix your levain. If you are very confident it's lively enough—it has reliably doubled in volume after feeding and is stretchy and webby—you can replace the levain in the following recipes with fed starter equal in weight to the parts of the levain combined.