Mix 1 cup whole grain flour with 1 cup lukewarm filtered water in a jar. Stir until smooth, cover loosely.
Place in a warm spot (70°F/21°C).
Let sit for 24 hours.
Discard half the starter. Add 1 cup all-purpose flour and 1 cup filtered water to the remaining mixture. Mix well.
Cover and let sit for 24 hours.
Repeat the Day 3 feeding process.
Feed daily: discard half, add 1 cup flour and 1 cup filtered water.
