The old way:  Mix 1 cup flour with 1 cup filtered water in a large ceramic bowl. Cover it with a light-weight cloth and leave it out in a warm spot indoors for 3 days. The problem... you might catch an airborne yeast that doesn’t make good-tasting bread, or you might not catch one at all. (If it doesn’t smell sweet and yeasty, it isn’t right!)

The surer way:  Dissolve 1 package dry baker’s yeast in1/2 cup lukewarm water in a large ceramic bowl and let it stand for 10 minutes while it works. Stir in another1/2 cup water, 1 tsp. sugar, and 1 cup flour, mixing well. As above, let it stand covered for 3 days in a warm spot, stirring it down once a day.

To reactivate the starter:  Stir it up and "feed" it 1 cup lukewarm water,1/2 cup flour, and 1 tsp. sugar. Cover and let it stand in a warm spot until it foams.

To replenish it after you use some:  Stir in some more flour and water.