Simple Bread — home baking · sourdough starter
A sourdough starter is flour and water left to ferment until wild yeast and lactic acid bacteria colonise the mix. You do not buy yeast in a packet—you maintain a living culture in a jar on the counter or in the fridge.
Day one: stir equal weights of wholemeal flour and lukewarm water in a clean jar. Cover loosely so gas can escape. By day three you should see bubbles and a faint tangy smell. If nothing happens, keep feeding daily; cooler kitchens need more patience.
Feeding means discarding half the starter (or baking with the discard) and refreshing with fresh flour and water. Most home bakers feed once a day at room temperature, or weekly if the starter lives refrigerated between bakes.
When the starter doubles within four to six hours after feeding and smells pleasantly sour—not like nail polish remover—it is strong enough to leaven a loaf. Mix a portion into your dough from Simple Bread and skip commercial yeast entirely.
Hydration matters: a wetter starter (100% or higher) ferments faster and suits open-crumbed breads; a stiff starter behaves more predictably in warm weather. Write your ratios on the jar lid so you can repeat what worked.