Sourdough English Muffins

Name: Sourdough English Muffins
Ingredients: 2 tablespoons (25g) sugar; 2 cups (454g) warm water (110°F-115°F); 1 tablespoon active dry yeast or; 1 cup (227g) sourdough starter ripe (fed) or discard; ripe will give you a more vigorous rise; 7 cups (843g) King Arthur Unbleached All-Purpose; 1/2 cup (56g) Baker's Special Dry Milk or nonfat dry milk; 4 tablespoons (57g) butter at room temperature; 1 tablespoon (18g) salt; 1/4 teaspoon sour salt (citric acid) optional; for enhanced sour flavor; semolina flour or cornmeal for coating