Transfer the dough to a large, lightly oiled bowl and cover with plastic wrap. Let rise in a warm, draft-free place until doubled in bulk, about 2 hours, depending on the temperature of your kitchen.
Scrape the dough out onto a floured surface; it will be tacky. Dust the top of the dough lightly with flour. Roll one-third of the dough into a ball and set it on a wheat bran?dusted or lightly floured baking sheet. Dust the loaf with wheat bran and cover with a cloth. Let rise until doubled, about 1 hour.
Preheat the oven to 450°. Preheat a 3-quart enameled cast-iron casserole. Transfer the dough to the casserole, cover with the lid and bake for 40 minutes. Uncover and bake the loaf for 5 to 10 minutes longer, until browned. Transfer the loaf to a rack and let cool.
Pat the dough out about 1 inch thick on a lightly oiled 12-by-18-inch baking sheet. In the center of the dough, mix 2 tablespoons of olive oil with 1/2 teaspoon of salt and 1/2 tablespoon of water until blended, then rub the mixture all over the dough. Using your fingertips, dimple the dough all over. Let rise, uncovered, for 1 hour, or until doubled.
Sprinkle the focaccia with rosemary and salt and bake it at 450°for 20 to 25 minutes, until risen and nicely browned.