I adapted this approach from The Perfect Loaf. King Arthur Flour, the Tartine bread book, and every other sourdough-related book or website also has a guide available. The basic approach is to start with a whole-grain or rye flour (since they contain more yeasts and bacteria) and higher hydration, switching to white flour and 100% hydration (what?) once the culture takes hold.
- Dark rye flour
- Unbleached all-purpose flour
- Start with an all-rye, 150% hydration mixture. Cover loosely and incubate at room temp. (I started my culture in San Francisco’s cool season, so I kept my starter in the oven with the light on during this stage.) Every day, create a new starter with 150% hydration and 100% of the previous day’s starter (e.g., 10g rye flour, 10g starter, and 15g water). After about a week, the starter should be doubling in volume in 8-12 hours, then slowly falling.
- Once the starter is well-established, transition to a dryer mixed-flour recipe. Use 100% hydration, 20% starter, and a 50-50 rye/all-purpose flour mix. Feed daily. I only bake occasionally, so I keep a small culture (30g of flour daily).
- Optionally, preserve some of your well-established culture. Mix a big dollop of active starter with a scoop of the dry flour blend you’ve been feeding it. Incorporate with a spatula, then break apart clumps with your fingers. Continue breaking up clumps and adding flour until the mixture feels completely dry, then leave it to finish drying at room temperature for a few hours. Seal it in a jar and store it away from light and moisture. Revive by mixing the whole jar (or enough of it to get a healthy dose of your original starter) with 50g fresh flour and enough water to make it easy to stir. Mix until no dry bits remain, incubate at a warm room temperature until bubbly (usually 12–24 hours), then feed as usual.
- Feeding the starter at the same time every day is helpful.
- Chlorinated or chloraminated water will kill your culture. Remove chlorine by leaving the water in an open container at room temperature for a few hours. San Francisco tap water is chloraminated, which is easiest to (mostly) remove by running it through a Brita pitcher.
- King Arthur Flour sells fresh, wet starter online. I haven’t tried it—if it works, it’d cut a lot of the guesswork out of this process. Some bakeries (including The Mill in SF) will also sell or give away their starter.