This is the potato starter:
* 1 or 1½ cups regular sourdough starter
* 1½ cups warm water
* 2 cups bread flour
* 1 tbsp vital wheat gluten (optional)
* 1 cup mashed potatoes
This is the bread dough:
* 3/4 cup warm water
* 2 teaspoons kosher salt (if using table salt, use 1½ tsp)
* 1 tsp active dry yeast
* 1/3 cup oil or melted butter
* 1/3 cup sugar
* 6½ to 7 cups bread flour, added gradually
Recipe
Combine starter, water, flour, gluten & mashed potatoes; mix well, cover, and let set in a warm place until it froths up very light & bubbly. (in a cooler place, it will still froth up - it just takes longer. And if the starter is ready before I'm ready to bake, I just stick it in the fridge until I have time to bake)
Stir the mixture and add the remaining ingredients, using only half of the flour. Beat it until smooth & begin adding the remainder of the flour until dough is pretty firm.
Turn the dough out onto a lightly floured board and knead in only enough additional flour to prevent it from being sticky. When the dough is smooth and elastic, place it in a large bowl in a warm place, cover and let rise until double in bulk.
Punch down the dough and divide it into three equal portions. Shape each portion into a loaf and place in greased 8½x4½ loaf pans. Cover and let rise in a warm place until double in bulk. It should rise nicely above the rim of the pans.
Bake for 35-40 minutes in preheated 375° oven until golden. It should test 190° on an instant thermometer.
Remove from pans, oil the tops if you like, and turn out onto a cooling rack.