Combine warm water and yeast in a 2 cup glass measuring cup; let stand 5 minutes. Stir together flour and salt in a large mixing bowl; add yeast mixture, stirring to combine. Cover bowl with plastic wrap. Let dough stand at room temperature for a least 8 hours, preferably 12 – 18 hours. Spoon dough onto a lightly floured work surface; sprinkle lightly with additional flour; fold sides over once or twice. Cover loosely with plastic wrap and let dough rest 15 minutes.
Cover and bake 30 minutes; uncover, and bake an additional 15 minutes, or until the loaf is golden brown. Remove bread from Dutch oven and cool on a wire rack at least 1 hour before slicing.
Coat a clean, smooth towel withflour, bran or cornmeal. Shape dough into a round using just enough additional flour to keep doughfrom sticking to fingers or the work surface; place dough, seam side down, on prepared towel. Cover with another towel; let rise in a warm place (85 degrees), free from drafts, 1 to 2 hours or until doubled in size and dough does not readily spring back when pressed with a finger.
At least 30 minutes before bread has finished rising, preheat oven to 475 degrees. Place a 4 to 6 quart cast iron Dutch oven (with lid) in the oven as it heats.
When dough has doubled in size, carefully remove Dutch oven; set lid aside. Uncover dough; slide your hand under the bottom towel and carefully turn dough into the preheated pot, seam side up. The dough will lose its shape in the process. Gently shake the pan to distribute the dough more evenly. Do not try to make it perfect; it will straighten out as it bakes.