Sourdough boule

The boule — French for 'ball' — is the canonical sourdough loaf shape and serves as the standard home sourdough preparation worldwide. The technique applies broadly to any hand-shaped round loaf made from a high-hydration dough leavened only with sourdough starter, salt, water, and flour. There is no commercial yeast in a true sourdough boule; the rise comes entirely from the starter's wild yeast community.

The modern home sourdough boom (2010s-present, accelerated dramatically by 2020 pandemic baking) has produced an unusually well-documented technique baseline. A standard recipe: 500g bread flour, 350g water (70% hydration), 100g active starter (20% by flour weight), 10g salt (2%). Bulk ferment 4-6 hours at room temperature with periodic folds; pre-shape and rest 30 minutes; final shape into a banneton (proofing basket); cold-retard in the refrigerator 8-48 hours; bake from cold in a hot covered Dutch oven (230°C / 450°F) for 20 minutes covered + 20-25 minutes uncovered.

The key technical insight is that sourdough's slow fermentation produces structural and flavor characteristics commercial yeast cannot replicate. The long cold retard develops complex flavor compounds (esters from the wild yeasts, lactic and acetic acid notes from the bacteria) and gives the gluten time to relax into the open, irregular crumb that distinguishes sourdough from commercial bread. A loaf that ferments and bakes in 4 hours (commercial yeast) is structurally and flavor-wise a different bread from one that ferments for 36 hours total.

The Dutch oven technique (or a covered cloche, or a steam pan) is essentially non-negotiable for home sourdough. Commercial bakery ovens inject steam for the first 10-15 minutes of baking; home ovens don't have steam injection, so the covered vessel traps the bread's own moisture and creates the same effect. Without steam, the crust sets too fast and prevents the dramatic 'oven spring' rise that defines a good boule.