In large bowl, whisk together 5 cups of the flour, the salt and yeast. Stir in warm water until well combined; cover with plastic wrap. Let rise in warm draft-free place until doubled in size, about 12 hours. (Make-ahead: Let rise for up to 18 hours.)
Sprinkle work surface with 1/3 cup of the remaining flour. Scrape dough onto work surface; sprinkle with 1/4 cup of the remaining flour. Cover with tea towel. Let stand for 15 minutes.
Using floured hands, press dough into 1-inch thick circle. Fold dough, 1 1/2 inches from edge farthest from you, pressing with hands; repeat folding, pressing into torpedo shape. Pinch seams to seal.
Dust rimless baking sheet with cornmeal. Place dough, seam side down, on pan; cover with clean tea towel. Let rise until doubled in size, about 1 1/2 hours.
Using scissors, cut 3 slashes crosswise on surface of dough. Sprinkle with 1 tbsp of the remaining flour. Bake in 425°F oven for 10 minutes. Decrease heat to 375°F; bake until light golden and loaf sounds hollow when tapped, about 30 minutes. Serve warm or let cool on rack. (Make-ahead: Let cool completely; wrap in plastic wrap. Freeze in resealable freezer bag for up to 3 weeks; thaw in bag at room temperature. Reheat in 325°F oven until warm, about 5 minutes.)
Tip from The Test Kitchen: Your microwave is the ideal place to let the dough rise quickly. It's well insulated, so it can protect the yeast from any drafts during fermentation.
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