Mix equal parts flour and water in a clean jar
Use 1/2 cup flour and 1/4 cup water to start
Stir until no dry flour remains
Cover loosely with a lid or cloth
Leave at room temperature for 24 hours
Discard half of the mixture
Feed with equal parts flour and water again
Stir well and cover loosely
Repeat feeding every 24 hours
Keep at room temperature
Continue for 5 to 10 days
Watch for bubbles and a sour smell
Use when it doubles in size within 4 to 8 hours after feeding
Store in the refrigerator if not using daily
Feed regularly to keep it active