1 1/2 cups warm water
1 cup Sourdough Starter
4 cups unsifted all-purpose flour
3 teaspoons granulated sugar
1 1/2 teaspoons salt
2 to 2 1/2 more cups unsifted
1/2 to 1 teaspoon baking soda
Combine water, starter, the 4 cups flour, sugar and salt in a crock or glass bowl. Mix well, cover lightly with a towel or cheesecloth folded into several thicknesses, and let stand at room temperature for approximately 18 to 24 hours or until the dough has doubled in size.
Mix 1 cup of the remaining flour with 1/2 teaspoon of the baking soda and stir this into the risen dough until it is very stiff. Turn the dough out onto a floured board and knead approximately 1 more cup of flour and a little more baking soda into it. Knead it for 5 to 10 minutes or until the dough is smooth.
Shape into 2 long loaves or 1 large round loaf, place on a lightly greased baking sheet, cover, and let stand in a warm place for 3 to 4 hours or until almost doubled in size.
Preheat oven to 400 degrees F.
Brush a little water on top of the loaves and make a few diagonal slits across the top with a sharp knife. For a crustier bread, place a shallow pan of water in the bottom of the oven. Bake for approximately 45 to 50 minutes or until the crust is a medium dark brown.