Mix equal parts flour and water in a clean jar
Stir until no dry flour remains
Cover loosely and leave at room temperature
Feed daily with equal parts flour and water
Discard part of the starter before each feeding
Continue feeding until it becomes bubbly and doubles in size
Use it for baking when it is active and reliably rising
Keep feeding regularly to maintain it
Refrigerate it if you bake less often
Bring it back to room temperature and feed before use