I made this with the originally recommended amount of salt. I'd suggest halving the salt unless you like really salty bread.
Measure the rosemary *after* chopping.
In a bowl, dissolve the yeast in the water. Allow to proof for three minutes.
Stir the sponge and 3 tablespoons oil into the water, breaking the sponge up using your hands or a spoon. Stir in the rosemary and salt.
Add 3 cups of the unbleached flour, the whole wheat flour, and salt and mix, scraping and folding until the dough gathers into a single mass which will be wet and sticky with strands hanging from your fingers.
Turn the dough out onto a lightly floured surface and allow to rest for 3 minutes. knead in as much of the 1/3 cup of flour as is required to make a smooth, elastic and only slightly sticky dough (use as little flour as is possible). Shape into a ball.
Place the dough in a lightly oiled bowl, brush the top of the dough with additional oil, and cover with plastic wrap and refrigerate overnight.
Remove from the refrigerator and allow to warm-up in a draft-free spot for two hours.
Sprinkle a baking sheet without sides generously with cornmeal. On a floured work surface, halve the dough and then shape one piece into a ball, pressing to remove any large bubbles at the edges. Place the dough-ball on the baking sheet, being sure to put the seam on the bottom. Repeat with the second ball, leaving 3 to 4 inches between the two. Cover with plastic and allow to rise until doubled, in a draft-free location. This should take 2-2 1/2 hours. These loaves will be flat and wide.
Preheat the oven for at least thirty minutes along with a baking stone or tiles on the middle rack to 425. Place a baking pan with decent sides on the bottom shelf. Boil two cups of water. Brush the loaves again with oil and then, using a razor blade, make a tic-tac-toe pattern in the top of each of the loaves - do not tear the dough, you want to cut it. Pour the boiling water into the baking pan. Slide the loaves off the sheet and onto the stone.
Bake for 20 minutes, reduce the temperature to 350 and then bake for another 30-35 minutes until the loaves are a light golden brown and hollow sounding when tapped on the bottom. When done, brush with additional olive oil and transfer to cool on a rack.