1. Combine Starter, Water, and Salt: In a large mixing bowl, gently whisk together the active sourdough starter, warm water, and salt until the salt is fully dissolved and the starter is mostly dispersed. The mixture will look milky and slightly bubbly.

2. Add Flour and Mix the Dough: Gradually add the all-purpose flour to the wet ingredients. Use a sturdy spoon or your hands to mix until a shaggy dough forms and no dry streaks of flour remain. Avoid overmixing at this stage; just ensure everything is incorporated. The dough will be sticky.

3. Perform Stretch and Folds for Strength: Cover the bowl with a clean kitchen towel or plastic wrap. Let the dough rest for 30 minutes. After resting, perform your first set of “stretch and folds.” With wet hands, grab a portion of the dough from the edge, stretch it upwards, and fold it over the center. Rotate the bowl a quarter turn and repeat this process 3-4 more times until you’ve gone around the entire dough. Repeat this stretch and fold process every 30 minutes for a total of 3-4 times over the next 1.5 to 2 hours. You’ll notice the dough becoming smoother and more elastic with each set.

4. Bulk Fermentation (First Rise): After the stretch and folds, cover the bowl again and let the dough rest at room temperature (ideally around 70-75 F) for 2-3 hours, or until it has visibly increased in volume by about 30-50% and looks bubbly. The dough should feel light and airy.

5. Shape the Baguettes: Gently turn the dough out onto a lightly floured surface. Divide the dough into 2 or 3 equal portions, depending on your desired baguette size. Gently pre-shape each portion into a loose cylinder or rectangle, then let them rest for 15-20 minutes, covered, to relax the gluten. To form the baguettes, take one piece of dough, gently flatten it into a rectangle. Fold the top edge down to the center and press to seal. Fold the bottom edge up to meet the top, and press to seal again. Then, fold the entire dough in half lengthwise and seal the seam firmly with the heel of your hand. Gently roll the dough back and forth to lengthen it into a baguette shape, tapering the ends slightly. Aim for a length that fits your baking sheet.

6. Proof the Baguettes: Carefully transfer the shaped baguettes to a floured couche (a linen cloth designed for proofing baguettes) or a baking sheet lined with parchment paper and floured kitchen towels folded to create “flutes” between the loaves. Dust the baguettes lightly with flour. Cover them loosely with plastic wrap or a clean towel and let them proof at room temperature for 1-2 hours, or until they look puffy and slightly larger. They should pass the “poke test” – when gently poked with a floured finger, the indentation should spring back slowly.

7. Prepare for Baking and Score: Preheat your oven to 450 F (230 C) with a baking stone or heavy baking sheet inside. If you have a Dutch oven or a steam tray, place it in the oven to preheat as well. Just before baking, carefully transfer the baguettes to the hot baking stone/sheet. Using a very sharp knife or a razor blade (lame), make 3-5 diagonal slashes across the top of each baguette, about 1/4 to 1/2 inch deep. This allows the bread to expand properly.

8. Bake with Steam: If using a steam tray, pour about 1/2 cup of hot water into it immediately after placing the baguettes in the oven (be careful of steam!). Bake for 25-30 minutes, or until the baguettes are deep golden brown and sound hollow when tapped on the bottom. If your oven has a convection setting, you can use it for the last 5-10 minutes for extra crispiness. Let cool on a wire rack before slicing and serving.