I use active yeast and mix with water first to proof it. After 5 minutes, mix in flour with plastic or wood utensil until starter leaves side of bowl. I like to use a glass mason jar with lid. Let sit at least 6 hours in warm place until it triples, refrigerate if not using right away(take out and leave at room temperature for an hour before use).
Mix in 4 1/2 cups of flour (I used 2 cups whole wheat and the rest white), water, sponge starter, salt. Knead for about 10 minutes. Dough should be sticky, but not stick to your hands. Place in lightly oiled bowl and turn over once to coat.
Let rise until double in bulk (about 2-3 hours).
Punch down and shape into 2 loaves on 2 cookies sheets dusted with flour.
Place in warm place (I heat oven alittle and place in it .)Let rise until double.
Preheat oven to 450. Place a small pan on lower shelf to hold 2 cups of boiling water. Score top of loaves with and x.
Place boiling water in pan on lower shelf, place loaves on center shelf and bake for 40 minutes. I baked mine for 30. Bottom of bread should sound hollow. I agree as stated by reviewer, 450 degree was too high a temperature for full 40 minutes. I baked until golden brown all over for 30 minutes, turned off oven with bread inside for last 10 minutes directly on rack.
Turn off oven and let sit for 10 minutes to develop crust. Take out and let cool off on cooling rack. I served with my recipe for roasted garlic.