Feed your starter 8-12 hours before mixing, using equal parts starter, flour, and water by weight. It's ready when it has doubled in size and passes the float test.
Whisk warm water and active starter together until fully dissolved. Add bread flour and stir until a rough, shaggy dough forms. Cover and rest for 30 minutes.
Sprinkle salt over the dough and squeeze it in with wet hands until fully incorporated. Cover and rest for another 30 minutes.
Perform 4 sets of stretch and folds, spaced 30 minutes apart. After each set, cover and rest. Then leave covered for bulk fermentation until the dough grows by 50-75% and feels airy.
Turn the dough onto a floured surface. Fold the edges toward the center to form a ball, then build surface tension by dragging it toward you with a bench scraper. Rest for 20 minutes.
After the bench rest, stretch the dough into a circle, fold the bottom third up and the top third down, then roll tightly toward you. Place seam-side up in a rice-floured banneton.
Cover the banneton loosely and refrigerate for a minimum of 8 hours and up to 16-18 hours for cold proofing and flavor development.
Preheat your Dutch oven with the lid on in the oven at 500°F (260°C) for 45-60 minutes.
Turn the cold dough out onto parchment paper seam-side down. Score the top confidently with a lame at a 30-45 degree angle, about 1/2 inch deep.
Lower the dough into the Dutch oven using the parchment paper handles. Cover and bake at 500°F (260°C) for 20 minutes. Then remove the lid, reduce temperature to 450°F (230°C), and bake for another 20-25 minutes until deep golden brown.
Transfer the bread to a wire cooling rack and let it cool completely for at least 1 hour (preferably 2) before slicing.