Dissolve yeast in 1/2 cup warm water until frothy. Stir in remaining 2 cups water, the flour, and sugar or honey. Beat until smooth. Cover with cheesecloth. Let stand at room temperature for 5-10 days or until bubbly; stir 2-3 times each day.
To store, transfer starter to a jar and cover with cheesecloth; refrigerate. DO NOT cover jar tightly with a metal lid.
To use starter, bring desired amount to room temperature.
To replenish starter after using, stir 3/4 cup all-purpose flour, 3/4 cup water, and 1 tsp sugar or honey into remaining amount. Cover; let stand at room temperature at least 1 day or until bubbly. Refrigerate for later use.
If starter isn't used within 10 days, stir in 1 teaspoon sugar or honey. Repeat every 10 days until used.