Place flours, salt, starter and water in mixing bowl.
Begin mixing at low speed (#2 on Kitchen Aid Mixer with a dough hook) for 5 minutes. After 5 minutes, increase speed (#4 on Kitchen Aid Mixer) for 2 more minutes.
The temperature of the dough should be between 72°F and 80°F. The dough should be soft to the touch and moist feeling, but should not stick to fingers. Place dough in a bowl that had been lightly dusted with flour. Cover with plastic and let rise for 1 hour. Fold the dough by lifting each of the corners of dough and folding them into the center. Cover the dough with plastic and return to a warm, draft-free place for another hour. Repeat this folding process a second time, and let rest for a third hour.
Since you are making one loaf, no dividing is needed.
Shape the dough into a boule. Lightly dust a banneton with flour. Place the dough in the banneton, seam side up. Throw a light film of flour over the top to keep the plastic from sticking, and cover tightly with plastic wrap.
Let the dough proof for 2½-3 hours in a warm, draft-free place.
Place a piece of parchment paper on a bread peel. Turn the dough onto the peel, bottom side up. Using a single-edged razor blade, score the loaf, just barely breaking through the skin and cutting about ⅛ inch into the dough. Bake at 450°F for about 40 minutes until the bread is a deep golden brown with a crisp crust and sounds hollow when tapped on the bottom.