1 pkg. active dry yeast
2 1/2 c. warm water
2 c. sifted all-purpose flour
1 tbsp. sugar

Dissolve yeast in 1/2 cup water. Stir in remaining water, flour, and sugar. Beat until smooth. Cover with cheese cloth; let stand at room temperature for 5 to 10 days (time required will depend upon room temperature; if room is warm, let stand a shorter time than if room is cool). Cover and refrigerate until ready to use.

To keep starter going, add 3/4 cup water, 3/4 cup sifted all-purpose flour, and 1 teaspoon sugar to remaining starter after some is used. Let stand at room temperature until bubbly and well fermented at least 1 day. Cover and refrigerate until used again. If not used within 10 days, add 1 teaspoon sugar. Repeat, adding sugar every 10 days.