1. Combine Starter, Water, and Flour: In a large mixing bowl, gently combine your active sourdough starter with the warm water. Stir until the starter is mostly dissolved. Add the bread flour and mix with a spoon or your hands until no dry streaks of flour remain. It will be a shaggy, somewhat sticky dough. Cover the bowl with a damp cloth or plastic wrap and let it rest for 30 minutes. This is called autolyse, and it helps the flour hydrate.

2. Add Salt and Begin Folding: After the autolyse, sprinkle the salt over the dough. Gently work the salt into the dough by squeezing and folding it for a few minutes until it’s fully incorporated. The dough might feel a bit stiff at first.

3. Perform Stretch and Folds: Over the next 2-3 hours, you’ll perform a series of “stretch and folds.” Every 30-45 minutes, lightly wet your hands. 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 times until you’ve gone all the way around. This builds strength in the dough. You should do 4-6 sets of these folds. The dough will become smoother and more elastic with each set.

4. Bulk Fermentation: After your last set of folds, cover the bowl again and let the dough rest at room temperature for the remainder of the bulk fermentation, which can be another 1-3 hours. The dough should increase in volume by about 20-30% and look bubbly on the surface. This stage is crucial for flavor development.

5. Shape the Dough: Lightly flour your work surface with rice flour or all-purpose flour. Gently turn the dough out onto the surface. Carefully shape the dough into a round or oval. You can do this by gently pulling the edges of the dough towards the center, creating tension on the surface. Avoid deflating it too much.

6. Final Proof (Cold or Warm): Place the shaped dough seam-side up into a floured banneton basket or a bowl lined with a floured kitchen towel. Cover it loosely with plastic wrap. For a warm proof, let it sit at room temperature for 1-4 hours until it looks puffy and springs back slowly when gently poked. For a cold proof (recommended for flavor and convenience), refrigerate it for 8-12 hours, or even up to 24 hours.

7. Preheat Oven and Bake: About 30-45 minutes before baking, place a Dutch oven (with its lid) into your oven and preheat to 450 F (232 C). Once preheated, carefully remove the hot Dutch oven. Gently invert your dough from the banneton into the hot Dutch oven. Score the top of the dough with a sharp knife or razor blade (a single slash is perfect for beginners).

8. Bake and Cool: Place the lid back on the Dutch oven and bake for 20 minutes. Remove the lid and continue baking for another 10-15 minutes, or until the crust is a deep golden brown. The internal temperature should be around 200-210 F (93-99 C). Carefully remove the loaf from the Dutch oven and transfer it to a wire rack to cool completely for at least 1-2 hours before slicing. This cooling time is essential for the crumb structure to set.