Mix starter, about 2 cups of the flour and milk in a large mixing bowl (not metal). Cover and let set overnight. In the morning, mix 1/4 cup flour with the sugar, salt and soda. Sprinkle over the dough and mix in thoroughly. Add more flour if needed to make a stiff dough. Knead on a lightly floured board until no longer sticky. Roll out dough to 3/4-inch thickness and cut out with a 3-inch biscuit cutter or a large glass. Place muffins 1 inch apart on a cookie sheet which has been sprinkled with cornmeal. Sprinkle more cornmeal on top.