1 1/2 teaspoons bread machine or quick active dry yeast
4 cups lukewarm water (105°F to 115°F)
3 cups all-purpose flour or Better for Bread bread flour
4 teaspoons sugar
Dissolve yeast in warm water in large glass bowl. Stir in flour and sugar. Beat with electric mixer on medium speed about 1 minute or until smooth. Cover loosely; let stand at room temperature about 1 week or until mixture is bubbly and has a sour aroma. Transfer to 2-quart or larger nonmetal bowl with tight-fitting lid. Refrigerate until ready to use.
Make Sourdough Starter at least 1 week before making bread. Stir cold starter; measure cold starter, and let stand until room temperature (starter will expand as it warms up).
Care of Sourdough Starter: Use Sourdough Starter once a week or stir in 1 teaspoon sugar. After using starter, replenish it by stirring in 3/4 cup all-purpose flour, 3/4 cup water and 1 teaspoon sugar until smooth. Cover loosely; let stand in warm place at least 1 day until bubbly. Cover tightly; refrigerate until ready to use.