Weigh your flour; or measure it by gently spooning it into a cup, then sweeping off any excess. Stir all of the starter 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 starter rest longer; overnight (up to 16 hours) is best.

Stir down the starter with a spoon and add the water, yeast, sugar, 3 1/4 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 3/4 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). If you're going out, or if you prefer, let the dough rise slowly in the fridge. If your dough has been refrigerated, allow it to come to room temperature before shaping; it'll warm up and rise at the same time.

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. The smaller loaves will bake more quickly, so keep your eye on them.

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.