1. Make the starter: Stir together flour, yeast, and water with a rubber spatula in a medium bowl. Cover with plastic wrap, and let stand at cool room temperature until it has risen slightly and bubbles cover entire surface, 12 to 15 hours.

2. Make the dough: Whisk together flour and yeast in a large bowl. Add water and starter, and stir with spatula until mixture comes together in a slightly sticky, loosely formed ball of dough. Cover with plastic wrap and let rest for 20 minutes.

3. Gently turn dough onto an unfloured work surface. Sprinkle with salt.

4. To knead: Gather dough, lifting it above work surface. Hold one end of dough close to you while you cast the other end in front of you, onto the surface. Pull the end of dough in your hands toward you, stretching it gently, then fold the dough in half on top of itself. Repeat. Lift, cast, stretch, and fold. Knead the dough until it is smooth, supple, and elastic, 8 to 10 minutes. Use a dough scraper to clean the surface as needed, adding the scraps to the dough. (Dough will be very sticky, but avoid adding more flour until the end, when it may be necessary to add a very small amount. Add the flour to your fingers, not the dough.) Form into a ball.

5. Place dough in a lightly oiled bowl. Cover with oiled plastic wrap. Let rise at cool room temperature for 45 minutes.

6. Gently turn dough onto a lightly floured surface. (Do not punch down.) Fold into thirds, as you would a business letter. Then fold it in half crosswise. Return to bowl, cover, and let rise at cool room temperature until it has almost doubled, at least 75 minutes.

7. Gently turn dough onto a lightly floured surface. Using a dough scraper or a knife, divide dough into equal portions (3 if making baguettes, 2 if making boules or rolls). Cover with oiled plastic wrap, and let rest for 20 minutes.

8. On a lightly floured surface, spread each portion of dough into a rectangle that's roughly 10 by 6 inches. Fold dough into thirds again, as you would a business letter, pressing seams with your fingers. Shape portions into baguettes, rolls, or boules.