Start preparing the bread in the morning. In a very large bowl, combine water, salt, and yeast. Mix flour into the water until it is all wet. Cover with a towel (cheese cloth or plastic wrap can be used too) and let sit on the counter for 2-8 hours. When dough has at least doubled in size, separate into 8 small balls. Sprinkle two baking sheets with corn meal and put four balls on each sheet, separated and spaced out so as to not be touching. Cover with a towel or cheese cloth and allow to rise again.
While bread is rising the second time around, peel and cube potatoes. Add to a large pot of water and bring to a boil. Boil potatoes until just underdone; about 15-20 minutes. While potatoes are cooking, cook bacon if necessary; cool, crumble, and set aside. Drain potatoes and reserve 2-4 cups of the water you boiled them in. Set drained potatoes and reserved water aside separately.
Add butter and bouillon to the empty pot used to boil the potatoes. Chop onions and mince garlic; add to pot and sauté for 1-2 minutes. Add 1/4 cup of flour and stir until smooth.
Add milk and potato water alternately, 1/2 cup- 1 cup at a time. Stir until thickened between each addition and it's the consistency of a thick white sauce. Add the potatoes at the end.
Meanwhile, preheat oven to 450°F. Put a pan on the bottom rack and a basking stone (if you have one) on the middle rack while preheating. Slide loaves onto middle rack then pour water into bottom pan. Quickly close oven so steam will get trapped. Cook for 20-30 minutes, or until bread becomes brown on top.
Cut holes into bread loaves and pull out some of the inside, making a bowl. Add soup and top with shredded cheese, cooked bacon pieces, and more green onions if desired.
Serve with grapes.