Two days before making the bread, blend all the ingredients in the sour dough starter and leave in a warm place to ferment. After one day it should appear frothy and smell sour. On the second day it will look smoother, with only a few bubbles. Check it from time to time to see that it is working. Transfer to the refrigerator until needed. Following the basic loaf method, combine the loaf ingredients with the starter, but do not add the water until they are well mixed. Knead well and bake as before.