Levain
- 1.First: feed your starter 8 to 12 hours before you build the levain, so it's lively and bubbly when you need it. If you keep your starter in the fridge, pull it out and feed it the night before — a cold or sluggish starter is the most common reason home sourdough doesn't rise. New to sourdough or don't have a starter yet? Read the starter-from-scratch guide linked below — it walks the 7-day process to build one from flour and water.
- 2.To feed: in a clean jar, mix 10g of your existing starter with 50g flour and 50g water. (Roughly equal parts flour and water by weight, plus a small spoonful of the old starter — the ratio is 1 part starter to 5 parts flour to 5 parts water if you want the formal recipe-speak.) Stir until smooth, cover loosely, and leave on the counter.
- 3.You'll know the starter is ready when it has roughly doubled in volume, looks domed on top, smells lightly tangy and yeasty, and is full of small bubbles. Drop a teaspoonful in a cup of water — if it floats, you're good to go. If it sinks, give it another hour or two and check again.
- 4.Now build the levain itself. The night before mix day, combine 30g of your peaked starter, 75g bread flour, and 75g water in a jar. Mix until smooth, mark the level on the jar with a rubber band so you can see it grow, and leave covered loosely on the counter.
- 5.The levain is ready in the morning when it has roughly doubled, looks domed and bubbly, and passes the same float test — drop a small spoonful in water; if it floats, it's strong enough to leaven the bread. If your kitchen is cold, this can take longer; build it earlier next time or move the jar somewhere warmer.
The float test is a useful green light, not the rule. A levain can be ready without floating perfectly, but if it floats AND looks bubbly AND smells lively, you can move on with confidence.