This same-day sourdough bread has a crisp, golden crust and soft, airy crumb, and it is ready to bake in one day without an overnight proof. A warm fermentation spot helps the dough rise and develop properly within the same day.
Stir the starter into the lukewarm water in a large bowl until the water turns cloudy.
Add the bread flour and mix by hand or with a dough whisk until no dry flour remains. Cover and rest for 30 minutes.
Scatter the salt over the dough. With wet hands, pinch and fold until the salt disappears and the dough feels cohesive.
Cover and rest for 30 minutes, then do the first set of stretch and folds: lift one side up and over the center, rotate the bowl, and repeat four times.
Repeat the stretch and folds three more times at 30-minute intervals, four sets total.
Cover and bulk ferment somewhere warm at 78 to 82°F for 3 to 3.5 hours, until the dough has risen 50 to 75%, looks domed and airy, and shows bubbles along the sides of the bowl. Do not wait for it to double.
Turn the dough onto a lightly floured surface, fold it into a loose round, and rest uncovered 20 minutes.
Flatten into a rough rectangle, fold the long sides to the middle, and roll up from the short end into a taut log. Place seam side up in a floured oval banneton.
Cover and proof at room temperature 60 to 90 minutes, until puffy and a floured finger leaves a dent that fills back in slowly.
About 45 minutes before baking, put the covered Dutch oven in the oven and preheat to 450°F.
Turn the loaf onto parchment and score one long slash down the length, about half an inch deep and slightly off center.
Lower the parchment into the hot Dutch oven, cover, and bake for 20 minutes.
Remove the lid, reduce to 425°F, and bake for 20 to 25 minutes more, until deep golden brown. Turn off the oven, crack the door, and leave the loaf inside for 15 minutes.
Cool on a wire rack for at least 1 hour before slicing.
Notes
Temperature drives the timeline. At 70°F, the bulk ferment runs five to six hours instead of three.
Watch the 50 to 75% rise, not the clock.
No warm spot? Put the covered bowl in a turned-off oven or microwave with a cup of just-boiled water beside it.
Mark the dough's starting height on the outside of a clear glass bowl before bulk begins. It is the easiest way to judge the rise.
Cutting before the loaf has cooled for a full hour leaves the crumb gummy. The interior is still setting.
To convert to an overnight loaf, refrigerate the shaped bâtard in its banneton for 8 to 14 hours and bake straight from cold, adding about 5 minutes to the covered stage.
Store cut side down on a board or in a paper bag for two days. Freeze sliced for up to three months and toast from frozen.