Day 1: Mix your starter.
In a clean glass jar, stir together 1 cup all purpose flour and 1 cup room temperature water until smooth. The mixture should be thick like pancake batter. Scrape down the sides and cover the jar loosely with a lid or clean cloth.
Day 2: Check for early bubbles.
Open the jar and look for small bubbles on the surface. Even a few is a great sign. Remove half the mixture and discard it. Add 1 cup flour and 1 cup water back into the jar. Stir well. The batter should remain thick but stirrable.
Day 3: Feed again.
Your starter may look flat one moment and bubbly the next. This is normal. Discard half the mixture again. Add 1 cup flour and 1 cup water. Stir thoroughly. The smell might be slightly tangy or fruity.
Day 4: Watch for rising.
Repeat the discard and feeding. By now, your starter should rise and fall each day. A good sign is if the mixture doubles between feedings. The texture should be airy and filled with bubbles.
Day 5: Strengthen the starter.
Feed your starter again. If it doubles within 4 to 6 hours, it is ready for baking. If not, continue daily feedings until it consistently rises. The batter should look puffy and sponge-like.
Day 6 and beyond: Maintain it.
If you bake often, keep the starter on the counter and feed daily. If you bake weekly, refrigerate it and feed once every 5 to 7 days. A healthy starter should be bubbly, slightly tangy, and full of life.