In large bowl, sprinkle 1 pkg. active dry yeast over 1 1/2 cups warm water. Stir to dissolve. Add 1 cup starter and mix well. Add 4 cups flour, 2 tsps. sugar, 2 tsps. salt and stir vigorously 3 or 4 minutes.
Cover and let rise until double in size.
Mix 1/2 tsp. soda with 1 cup flour and stir into dough. Knead in the remaining 1 cup flour until dough is satiny - 5 to 10 minutes. Shape into loaves.
Place on greased baking sheets which are lightly coverred with cornmeal. Let rise until doubled.
