1. The flour type should match the type of flour you intend to use for your bread. The water should be as pure as possible. I use tap water.
2. Place flour in a container. Glass is ideal. Ceramic and plastic can work as well, though it may take on some flavor from certain plastics.
3. Add slightly less than an equal volume of water to the flour.
4. Stir or shake.
5. Cover and allow to rest eight to twelve hours in a warm—not hot—space.
6. Allow to rest in a cool space. A refrigerator works fine; some would argue that the slower the starter grows, the deeper flavor it accrues.
7. Regularly pour out excess moisture and feed the yeast with more flour. Add water to maintain texture. We find that a mixture with a higher viscosity tends to resist over-souring (rotting).