2 cups all purpose flour (do not use bread flour)
2 cups warm water
2 1/2 teaspoons (1 package) dry yeast
In large non-metallic bowl or container, mix together yeast, water and flour. Cover loosely and leave in warm place to ferment, 4 to 8 days, depending on temperature and humidity in the kitchen. Place on cookie sheet in case of overflow. Stir with non-metallic spoon once a day. When mixture is bubbly and has a pleasant yeast/sour smell, it is ready to use.
When you use starter to bake, set it out several hours ahead to get to room temperature. Stir down or drain off any liquid gathered on the top. Stirring it in will give the starter more of a sour taste, draining it off will keep it more mellow. Measure amount for recipe and replace with 1 cup warm water, 1 cup flour and 1/4 cup sugar. Mix well and leave out until bubbly about 12 hours. Refrigerate until next use. "Feed" once a week.
If mixture is ever pink, orange, or any other strange color, throw it out and start over.