1. Combine Ingredients: In a large mixing bowl, gently mix your active sourdough starter with the warm water until the starter is mostly dissolved. Add the flour and salt, then mix with a wooden spoon or your hands until a shaggy dough forms and no dry flour remains. Cover the bowl with a damp cloth or plastic wrap and let it rest for 30 minutes. This resting period, called autolyse, helps the flour absorb water and begin gluten development.

2. Perform Stretch and Folds: After the rest, begin the first set of stretch and folds. With wet hands, grab a portion of the dough from one side, stretch it upwards, and fold it over to the opposite side of the bowl. Rotate the bowl a quarter turn and repeat. Do this 4-6 times until you’ve worked your way around the dough. Cover and let rest for 30 minutes. Repeat this stretch and fold process three more times, for a total of four sets, each 30 minutes apart. The dough will become smoother and more elastic with each set.

3. Bulk Fermentation: After the last stretch and fold, cover the bowl and let the dough bulk ferment at room temperature (around 70-75 F) for 6-8 hours, or until it has visibly increased in volume by about 30-50% and looks bubbly. Alternatively, you can place it in the refrigerator for 8-12 hours (or overnight) for a slower, colder fermentation, which can enhance flavor.

4. Shape the Loaf: Lightly flour your work surface. Gently turn the dough out onto the floured surface. Carefully shape the dough into a round or oval loaf. You want to create tension on the surface of the dough without deflating it too much. Use a bench scraper to help you gather and tuck the edges underneath, creating a tight ball.

5. Second Proof (Cold Fermentation): Lightly flour a proofing basket (banneton) or a bowl lined with a floured kitchen towel. Carefully transfer the shaped dough, seam-side up, into the basket. Cover with plastic wrap and refrigerate for 8-12 hours (or overnight). This cold proof develops flavor and makes the dough easier to handle. If you’re in a hurry, you can proof at room temperature for 2-4 hours, but the cold proof is highly recommended.

6. Preheat and Bake: About an hour before you’re ready to bake, place your Dutch oven with its lid into your oven and preheat to 450 F (232 C). Once the oven and Dutch oven are fully preheated, carefully remove the hot Dutch oven. Gently invert the cold dough from the proofing basket into the hot Dutch oven. You can score the top of the dough with a sharp knife or razor blade (a lame) if desired, creating a decorative pattern and allowing for even expansion.

7. Bake with Lid On, Then Off: Place the lid back on the Dutch oven and bake for 30 minutes. After 30 minutes, carefully remove the lid and continue to bake for another 15-20 minutes, or until the crust is a deep golden brown and the internal temperature reaches 200-210 F (93-99 C).

8. Cool Completely: Carefully remove the bread from the Dutch oven and transfer it to a wire rack. This step is crucial! Let the loaf cool completely for at least 1-2 hours before slicing. Slicing too early will result in a gummy texture.