1. Combine Starter and Water: In a large mixing bowl, gently mix your active sourdough starter with the warm water until the starter is mostly dissolved. The mixture should look milky and slightly bubbly.

2. Add Flour and Salt: Add the bread flour and salt to the bowl. Mix with a wooden spoon or your hands until no dry flour remains and a shaggy dough forms. Don’t overmix; just ensure everything is incorporated. Cover the bowl with a clean kitchen towel or plastic wrap and let it rest for 30 minutes. This resting period, called autolyse, helps the flour fully hydrate.

3. Perform Stretch and Folds: After the rest, perform your first set of stretch and folds. With wet hands, gently grab a portion of the dough from the edge, stretch it upwards, and fold it over to the center. Rotate the bowl a quarter turn and repeat this process 3-4 more times, until you’ve worked your way around the dough. The dough will become smoother and more elastic. Repeat this stretch and fold process every 30 minutes for a total of 3-4 sets.

4. Bulk Fermentation (Overnight Proof): After the final set of stretch and folds, cover the bowl again and let the dough ferment at room temperature for 1-2 hours (depending on your kitchen temperature and starter activity). Then, place the covered bowl in the refrigerator for 10-12 hours, or overnight. This slow, cold fermentation develops flavor and makes the dough easier to handle.

5. Shape the Dough: The next morning, lightly flour your work surface with rice flour or all-purpose flour. Gently turn the cold dough out onto the floured surface. Shape the dough into a round or oval by gently pulling the edges towards the center, creating tension on the surface. For a rustic look, you can gently pinch the seams together at the bottom.

6. Prepare for Baking: Preheat your oven to 450 F (230 C) with a Dutch oven inside for at least 30 minutes. Carefully transfer your shaped dough to a piece of parchment paper. If desired, score the top of the dough with a sharp knife or razor blade in a simple pattern (like a cross or a single line) for decorative stitching and to help the bread expand.

7. Bake the Loaf: Carefully remove the hot Dutch oven from the oven. Using the parchment paper as a sling, gently lower the dough into the Dutch oven. Place the lid back on and bake for 30 minutes.

8. Finish Baking and Cool: After 30 minutes, remove the lid from the Dutch oven. Reduce the oven temperature to 425 F (220 C) and continue baking for another 10-15 minutes, or until the crust is deeply golden brown and sounds hollow when tapped on the bottom. Carefully remove the bread from the Dutch oven and transfer it to a wire rack to cool completely for at least 1-2 hours before slicing. This cooling step is crucial for the internal structure and flavor to set.