Heat the milk to between 90 and 100 F. Pour it into a clean 1-1/2 quart glass, plastic, or stainless bowl.
Stir in 3 T freshly opened low-fat yogurt. Let stand in a warm place for at least 24 hours.
After a curd has formed, gradually stir in 1 cup of all-purpose flour. Cover with Saran and let stand for 2 to 5 days in a warm place.
This procedure will yield about 1-1/2 cups of starter for each of the "servings" listed above. 5. Cover and store in the refrigerator.
NOTE: If liquid "hooch" turns pink during fermentation, discard and start over with fresh ingredients.