Preparation Pulse flour, salt, and vinegar in a food processor to combine. Stir together yeast and 1/3 cup water in a small bowl until yeast is dissolved, then let stand until foamy, about 5 minutes. (If mixture doesn't foam, discard and start over with new yeast.) With motor running, pour yeast mixture and remaining 1 1/3 cups warm water into flour mixture in processor, blending until dough forms a ball and pulls away from side of processor bowl, about 1 minute. Cover processor feed tube and let dough rise until it fills bowl, about 1 hour. Pulse several times to deflate dough. Generously oil bread pans with olive oil. Turn out dough onto a work surface and divide in half (dough will be very soft). Press 1 half into a 10- by 8-inch rectangle and fold in the 2 short outer sides to meet in the middle, pinching edges together. Turn over (seam side down), then roll and stretch into a 15-inch-long irregular loaf. Put loaf, seam side up, in bread pan and turn to coat with oil, leaving loaf seam side down. Repeat procedure with remaining dough. Let loaves rise, uncovered, in a warm draft-free place 30 minutes. Put oven rack in upper third of oven, then put a large roasting pan with 1 inch of water in it on bottom of gas oven or on lowest rack of electric oven. Preheat oven to 450°F. Make 3 shallow diagonal slashes down length of each loaf with razor. Bake loaves 30 minutes, then carefully remove pan of water from oven. Remove bread from pans and turn upside down on upper oven rack, then bake until golden and crusty all over, about 5 minutes more. Cool loaves on a rack.
Preparation Pulse flour, salt, and vinegar in a food processor to combine. Stir together yeast and 1/3 cup water in a small bowl until yeast is dissolved, then let stand until foamy, about 5 minutes. (If mixture doesn't foam, discard and start over with new yeast.) With motor running, pour yeast mixture and remaining 1 1/3 cups warm water into flour mixture in processor, blending until dough forms a ball and pulls away from side of processor bowl, about 1 minute. Cover processor feed tube and let dough rise until it fills bowl, about 1 hour. Pulse several times to deflate dough. Generously oil bread pans with olive oil. Turn out dough onto a work surface and divide in half (dough will be very soft). Press 1 half into a 10- by 8-inch rectangle and fold in the 2 short outer sides to meet in the middle, pinching edges together. Turn over (seam side down), then roll and stretch into a 15-inch-long irregular loaf. Put loaf, seam side up, in bread pan and turn to coat with oil, leaving loaf seam side down. Repeat procedure with remaining dough. Let loaves rise, uncovered, in a warm draft-free place 30 minutes. Put oven rack in upper third of oven, then put a large roasting pan with 1 inch of water in it on bottom of gas oven or on lowest rack of electric oven. Preheat oven to 450°F. Make 3 shallow diagonal slashes down length of each loaf with razor. Bake loaves 30 minutes, then carefully remove pan of water from oven. Remove bread from pans and turn upside down on upper oven rack, then bake until golden and crusty all over, about 5 minutes more. Cool loaves on a rack.