Autolyse: In a large bowl, mix flour and water until no dry spots remain. Cover and rest for 30–60 minutes.
Mix Dough: Add sourdough starter and salt. Fold and knead gently until fully incorporated. Dough will feel hydrated and slightly sticky.
Bulk Fermentation: Cover and let rise for 4–6 hours, performing a stretch-and-fold every 30–60 minutes during the first half. Dough should feel airy and puffy.
Shape the Loaf: Turn onto a floured surface, shape into a round or oval, and place seam-side up in a floured proofing basket.
Final Proof: Cover and proof 2–3 hours at room temperature, or refrigerate overnight for slower fermentation.
Preheat Oven: Heat Dutch oven or baking stone to 475°F (245°C).
Score and Bake: Transfer loaf carefully, score the top, cover, and bake 20 minutes. Remove lid and bake 20–25 more minutes until golden brown.
Cool: Cool completely on a wire rack before slicing.