Make the levain: Stir together 3 tablespoons (40 grams) warm water and sourdough starter in a large bowl until mostly dissolved. Stir in bread flour until no dry bits of flour remain. Cover bowl with a kitchen towel; let stand at warm room temperature (72°F to 75°F) until almost doubled in volume and small bubbles appear on surface, 2 to 3 hours.

Make the dough: Add 1 ¼ cups (284 grams) warm water to levain in bowl; stir until levain is mostly dissolved. Add bread flour; mix together using your hands until no dry bits of flour remain. Cover bowl with a kitchen towel; let rest at warm room temperature for 30 minutes.

Uncover bowl, and sprinkle dough with salt; add remaining ¼ cup (56 grams) warm water. Using a grabbing/squeezing motion with your hands, incorporate salt and water into dough until mostly smooth, 2 to 4 minutes. (Dough will initially separate into clumps but eventually will form a homogenous mixture.)

Cover bowl using a kitchen towel; let rest at warm room temperature until dough is smooth, elastic, and increases slightly in volume, 3 to 4 hours, stretching and folding dough in bowl every 30 minutes. To stretch and fold the dough, use wet hands to grab one side of dough, stretch it upward until you feel a slight resistance, and then fold it over to the opposite side. Rotate bowl by 90 degrees, and repeat 3 times, for a total of 4 folds.

Lightly dust top of dough with bread flour. Turn dough out, floured side down, onto a work surface. Using a bench scraper and your palms, pull dough toward you across work surface, rotating about 90 degrees as you drag it, to develop tension and form a taut ball. Drag and rotate dough ball 4 to 5 times. Cover with a kitchen towel; let rest for 30 minutes. Lightly dust top of dough with bread flour. Using a bench scraper and your palms, repeat dragging and pulling motion to re-form dough into a taut ball. Let dough ball rest on work surface to help seal bottom seam, about 1 minute. Meanwhile, line an 8- to 9-inch proofing basket or bowl with a linen kitchen towel or large cloth napkin; dust generously with rice flour.

Lift dough ball using a bench scraper or your hands, and invert into prepared proofing basket so that the smooth, rounded side is facing down. Cover dough with a kitchen towel; let stand at room temperature until dough slightly increases in volume, about 30 minutes. For a same-day bake, proceed to step 8. Or for a more complex flavor and chewier, blistered crust, chill dough in basket at least 8 hours or up to 18 hours. Preheat oven to 500°F for about 45 minutes with rack in lower third position. Let dough continue proofing at room temperature while oven preheats. (If dough was chilled, remove from refrigerator, and let stand at room temperature while oven preheats.) During final 20 minutes of preheating, place a 10-inch or larger bread pan with lid or a 5-quart or larger cast-iron Dutch oven with lid (enameled or non-enameled) in oven to preheat.

Uncover dough, and if surface is sticky, lightly dust with rice flour. Invert dough ball onto an 11-inch square sheet of parchment paper so that the rounded side is now on top. Using a bread lame or a very sharp, thin knife, quickly score a 6-inch-long, ⅓-inch-deep slash along top of loaf.

Remove bread pan from oven, and carefully place parchment paper with dough inside pan. Place lid on pan, and return to oven. Reduce oven temperature to 450°F; bake, covered, until bread is increased in volume, opened up at the score, and crust is a pale, light brown, about 25 minutes. Remove lid, and continue baking bread until golden brown and an instant-read thermometer inserted into center of bread registers 205°F, 8 to 14 minutes. Remove bread from pan, and transfer to a wire rack; discard parchment paper. Cool completely, about 2 hours.