1. 1. Activate Your Starter: In a large mixing bowl, combine the active sourdough starter with the warm water, sugar, and olive oil. Whisk gently until the starter is mostly dissolved and the mixture is well combined. It should look milky and slightly frothy, indicating your starter is alive and ready to work.

2. 2. Mix the Dough: Add the salt and 3 cups of the all-purpose flour to the wet ingredients. Mix with a sturdy spoon or your hands until a shaggy dough forms. Gradually add the remaining 1 cup of flour, a little at a time, until the dough comes together and pulls away from the sides of the bowl. It should still be somewhat sticky but manageable.

3. 3. Knead for Development: Turn the dough out onto a lightly floured surface. Knead for 8-10 minutes until the dough is smooth and elastic. You’ll notice it becoming less sticky and more pliable as you knead. A good test is the “windowpane test”: gently stretch a small piece of dough; if you can stretch it thin enough to see light through it without tearing, it’s ready.

4. 4. First Rise (Bulk Fermentation): Lightly oil a clean bowl. Place the kneaded dough in the bowl, turning it once to coat with oil. Cover the bowl with plastic wrap or a damp kitchen towel. Let it rise in a warm spot for 3-4 hours, or until it has nearly doubled in size. You’ll see bubbles forming on the surface, and the dough will feel light and airy.

5. 5. Shape the Loaf: Gently turn the risen dough out onto a lightly floured surface. Shape it into a rustic loaf or a round boule. For a sandwich loaf, you can gently pat it into a rectangle and then roll it up tightly, pinching the seam closed. If using a proofing basket (banneton), dust it generously with flour or line a bowl with a floured towel. Place the shaped dough seam-side up in the basket/bowl.

6. 6. Second Rise (Proofing): Cover the dough loosely with plastic wrap or a damp towel. Let it proof at room temperature for 1-2 hours, or until visibly puffy and soft to the touch. Alternatively, for a deeper flavor development and easier handling, you can refrigerate it overnight (8-12 hours). The dough should spring back slowly when gently poked.

7. 7. Prepare for Baking: Preheat your oven to 450F (230C) with a Dutch oven or baking stone inside for at least 30 minutes. Carefully remove the hot Dutch oven. If using a baking stone, lightly dust a baking sheet with cornmeal. Gently invert the dough onto a piece of parchment paper or the prepared baking sheet. Score the top of the loaf with a sharp knife or razor blade to allow for expansion.

8. 8. Bake the Loaf: Carefully transfer the dough (on parchment paper) into the hot Dutch oven, or place it directly onto the baking stone. Bake for 25 minutes with the lid on (if using a Dutch oven), then remove the lid and bake for another 10-15 minutes, or until the crust is deep golden brown and the internal temperature reaches 200-210F (93-99C).

9. 9. Cool Completely: Transfer the baked loaf to a wire rack and let it cool completely before slicing. This is crucial for the crumb to set properly and prevents a gummy texture. Resist the urge to slice it warm!