1. Combine the warm water and yeast in a large bowl and stir with a fork to dissolve the yeast. Let stand for 3 minutes.
2. Add the cool water and sponge to the yeast mixture and mix with your fingers for about 2 minutes, breaking up the sponge. The mixture should look milky and slightly foamy.
3. Add the flour and salt and mix with your fingers to incorporate the flour, scraping the sides of the bowl and folding the ingredients together until the dough gathers into a mass. It should be wet and sticky, with long strands of dough hanging from your fingers. If necessary, add 1 tablespoon of water.
4. Move the dough to a lightly floured surface and knead for about 5 minutes, until it becomes supple and fairly smooth. This is a sticky, wet dough; don’t be tempted to add a lot of flour to the work surface. Just dust lightly and use a dough scraper as necessary to loosen the dough from the table during kneading. All the dough to rest for 15 minutes, covered with oiled plastic wrap. (This rest period is the autolyse).
5. Knead the dough for 3 to 5 minutes, until it is stretchy and smooth yet still slightly sticky. Shape the dough into a loose ball, place it in a lightly oiled bowl, and turn the dough in the bowl to coat with oil. Cover the bowl tightly with oiled plastic wrap and let the dough rise at room temperature (75º – 77º) for about 1 hour, or until the dough looks slightly puffy but has not doubled.
6. Place the dough in the refrigerator for at least 8 hours, or preferable, overnight to let it relax, develop flavor, and become more manageable.
7. Take the dough from the refrigerator and let is sit at room temperature for 1 to 2 hours, until it warms up and starts to rise.
8. Flour a work surface well and gently dump the dough onto it. Divide the dough into 3 equal pieces (about 13 ounces each). Gently flatten one piece, pressing out some the air bubbles, and stretch it into a rectangle. Form the dough into a log and then into a short baguette about 12 inches long. The loaf will be loose and slightly irregular in shape. Cover an area at one side of the work surface with a thick layer of flour and place the load seam side down on the flour. Repeat with remaining pieces of dough, leaving plenty of space between the loaves –they will spread as they rise. Cover the loaves with well-oiled plastic wrap and let them rise for about 1 hour.
9. Thirty minutes before baking, preheat the over to 475º. Place a baking stone in the oven to preheat and position an oven rack just below the stone.
10. Sprinkle a peel very generously with cornmeal. Line an upside-down baking sheet with parchment paper and sprinkle very generously with cornmeal. Life one loaf and flip it over onto the peel so the floured side is on top. Gently tug on the ends to stretch the loaf to the full length of the peel (about 14 inches). Repeat with the remaining loaves, placing another one on the peel and the last one on the pan. Dimple each loaf with your finger in about six places, but don’t deflate them too much.
11. Be sure the loaves are loosened from the peel, then carefully slide them onto the baking stone. Place the pan of bread on the rack below the stone. Using a plant sprayer, quickly mist the loaves 8 to 10 times, then quickly shut oven door. Mist the loaves again after 1 minute. Then mist again 1 minute later.
12. Bake for about 10 minutes, then reduce the temperature to 450º and bake for 15 minutes longer, or until the loaves sound slightly hollow when tapped on the bottom and the crust is a medium to dark brown. (If the crust is not brown enough, the loaves will soften as they cool.) Transfer the bread to a rack to cool for at least 30 minutes before serving.