1. Day 1: The Initial Mix. In a clean, medium-sized glass jar, combine 1/2 cup (120g) unbleached all-purpose flour and 1/2 cup (120g) lukewarm filtered water. Stir vigorously until there are no dry spots and the mixture is smooth, resembling a thick pancake batter. Scrape down the sides of the jar.

2. Cover and Wait. Loosely cover the jar (e.g., with a lid not screwed on tightly, plastic wrap with a few holes, or a clean kitchen towel). Place the jar in a warm spot in your kitchen, ideally between 70-78 F (21-25 C), away from direct sunlight.

3. Day 2: First Observations. On day two, you likely won’t see much activity. Give it a quick stir, re-cover it, and return it to its warm spot.

4. Day 3: The First Feeding. By day three, you might start to see tiny bubbles and a slightly sour, yeasty smell. Discard about half of the starter (approximately 60g or 1/4 cup). Then, feed the remaining starter with 1/2 cup (120g) fresh unbleached flour and 1/2 cup (120g) lukewarm filtered water. Stir well until combined, scrape down the sides, and loosely cover.

5. Days 4-7 (or longer): Daily Feedings. Continue the feeding routine every 24 hours. Each day, discard about half of the starter, then feed it with 1/2 cup (120g) fresh flour and 1/2 cup (120g) fresh water. Your starter is ready when it consistently doubles in size within 4-8 hours after feeding, which usually takes 7-10 days.

6. Maintaining Your Active Starter. Once active, feed it daily if baking frequently. For infrequent baking, feed it, let it sit at room temperature for 1-2 hours, then store it in the refrigerator. When ready to bake, take it out, let it come to room temperature, and feed it 1-2 times over 12-24 hours until active again.