Make the starter several days ahead of time. In large non-metallic bowl, mix together dry yeast, 2 cups warm water, and 2 cups all purpose flour and cover loosely. Leave in a warm place to ferment, 4 to 8 days. Depending on temperature and humidity of kitchen, times may vary. Place on cookie sheet in case of overflow. Check on occasionally. 3.When mixture is bubbly and has a pleasant sour smell, it is ready to use. If mixture has a pink, orange, or any other strange color tinge to it, THROW IT OUT! and start over. Keep it in the refrigerator, covered until ready to use.