To make the preferment: Weigh your flour; or measure it by gently spooning it into a cup, then sweeping off any excess. Stir all of the preferment ingredients together to make a thick, pudding-like mixture. Cover with plastic wrap and let it rest for at least 2 hours. For best flavor, let the preferment rest longer; overnight (up to 16 hours) is best.
To make the dough: Stir down the preferment with a spoon and add the water, yeast, sugar, 3 ¼ cups (390g) of the flour, and the salt. The dough will be a loose, messy mass. Let it rest for 12 to 15 minutes, then stir it again; it should become more cohesive and a bit smoother.
Knead the dough, adding up to an additional ¾ cup (90g) flour (as necessary to make a soft dough), 10 to 12 minutes.
Place the dough in a lightly greased bowl or plastic container, cover with lightly greased plastic wrap, and let it rise until almost doubled (depending on the weather, this could be 1 to 2 hours).
Deflate the dough gently, but don't knock out all the air; this will create those 'holes' so important to French bread. For one large loaf, form the dough into a round ball; for two loaves, divide the dough in half and shape into two balls.
Place a semolina- or cornmeal-dusted piece of parchment paper onto a baking sheet. Gently place the ball(s) of dough on the baking sheet, seam-side down.
Cover the bread gently with lightly greased plastic wrap, and let it rise until it's puffy and about 40% to 50% larger, anywhere from 45 to 90 minutes.
Preheat your oven to 475°F.
Slash or cross-hatch the bread with a sharp knife or lame. Dust it with a little flour. Spritz water into the oven with a clean plant mister, and place the bread in the oven. Reduce the heat to 425°F and spritz with water every few minutes for the first 15 minutes of baking.
Bake the bread for about 25 to 30 minutes, or until it's a rich golden brown, and its interior temperature registers at least 190°F on a digital thermometer.
Remove the bread from the oven, and cool it on a rack. Store bread, loosely wrapped in paper, for a couple of days at room temperature; wrap it in plastic and freeze for longer storage.
