Day 1: In glass bowl, stir 50 grams flour and 50 grams warm water. Let sit at room temperature, covered.
Day 2: Add 50 grams flour and 50 grams warm water to bowl. Stir and let sit at room temperature, covered.
Day 3: Discard half the starter. Add 100 grams flour and 100 grams warm water. Stir and let sit at room temperature, covered.
Day 4: Discard half the starter. Add 150 grams flour and 150 grams warm water. Stir and let sit at room temperature, covered.
Day 5: Discard half the starter then pour remaining starter into Mason jar. Add 150 grams flour and 150 grams warm water. Stir and let sit at room temperature, covered.
Day 6: Discard half the starter. Add 200 grams flour and 200 grams warm water. Stir and let sit at room temperature, covered.
Day 7: Place warm water in bowl and add spoonful of starter to water. If it floats, it’s ready to make bread. If it sinks, repeat Day 6 instructions. If not floating by Day 10, throw out and start over.