Prepare the Sponge
Combine your reserved sponge (2 C) with:
4 C Water, warm
5 C Bread Flour
(My Mom and Grandma use a 1:1 ratio of measured water to flour. The above ratio is more a 1:1 ratio when the ingredients are weighed out. It makes for a slightly stiffer sponge and gives the yeast and bacteria (flavor givers) more to feed on over the time that I give the sponge to ferment).
Mix until relatively smooth (small lumps are fine). Try to incorporate as much air as you can. Let stand and ferment at room temperature until very bubbly (3-4 hours). After about 4 hours cover with plastic wrap and refrigerate for 12-24 hours. This refrigeration retards the growth of the yeast, while giving the good flavor-enhancing bacteria time to work. I have found that this gives my bread a sweeter and more pungent sour taste than if I immediately took the sponge and made bread.
Dough Time
The next day beat down your sponge and remove your starter reserve (2 C). Place the remaining sponge in your mixer and add the following:
2 1/2 Tsp Salt
4 C Bread flour
Using your mixers dough hook kneed the above until it is thoroughly combined (5 minutes). It will still be a moist and sticky dough. Let stand for 5 minutes to allow the flour to become fully hydrated.
Next slowly add an additional 1-2 C of bread flour until your dough is slightly tacky to the touch but does not stick to the sides or bottom of the bowl while kneading.
Once you have achieved a slightly tacky dough remove from mixer and let rest for 5 minutes. After the dough has rested I kneed by hand for an additional 3-5 minutes to form a nice stiff dough.
Place dough in a lightly greased bowl and let rise until it has doubled in size. Once doubled punch the dough down and kneed into a new ball. At this point you can either let the dough rise a second time (more flavor without the overnight rest), or you can form into loaves.
After the first or second rise form the dough into the desired shape. I usually make 3 1.5lb rectangular loaves (loaf pans). Let the dough rise until it is about an inch above the top of the loaf pan, or if making round loads until it has doubled in size.
Baking
If baking in metal loaf pans:
In an oven safe pan, boil 1-2 Cups of water and once boiling place at the bottom of the oven. Place the loaves on a middle shelf and turn the oven on to 375° F. After the oven has reached 375° use a spray bottle to spray the bottom and sides of the oven with water to generate steam. Do this again after 5 minutes and then again 5 minutes later. Total time baking at 375° will be 40-45 minutes. Remove loaves from pans and place on a cooling rack for at least 30 minutes, I prefer an hour.
If baking round loaves:
Cut a # sigh using a sharp oiled knife, being careful not to deflate the dough. In an oven safe pan, boil 1-2 Cups of water and once boiling place at the bottom of the oven. Place the loaves on middle shelf and turn the oven on to 450° F. After the oven has reached 450° use a spray bottle to spray the bottom and sides of the oven with water to generate steam. Do this again after 5 minutes and then again 5 minutes later. Total time baking at 450° will be 30 minutes
After 30 minutes at 450° remove the pan of water and change the oven temperature to 375° and then cook the loaves an additional 5 to 10 minutes.
As an aside. If I have only allowed the dough to rise one time and do not have time to let the loaves rise, bake, and then cool (approximately 4 hours) I will spray the newly formed loaves with oil, cover loosely with plastic wrap, and then refrigerate overnight. I then complete the rise the next day and then cook as above. I use this modification when I make my loaves in the middle of the week, over 3 days. I make the sponge after work on the 1st day, make the dough, let it rise the 1st time, and form the loaves on the 2nd day. And then on the 3rd day I let the dough rise in the pans and bake the loaves and let them cool. I actually prefer this method over the 2 day method as it gives me a slightly moister, flavorful loaf.