• In a bowl, stir together your starter, flour, and water until fully combined.
• Transfer to a clean jar, cover loosely, and let sit for at least 4 hours until it’s well-doubled but before it collapses.

The Dough

• When the levain is nearly doubled, begin the autolyse. In a large bowl, mix your main bread flour and water with wet hands into a shaggy mass. Cover and rest for 1 hour.
• Add the levain and salt. Using wet hands, squeeze and fold until everything is evenly incorporated. Using wet hands, knead and squeeze briskly for 2–3 minutes and give it a few slap and folds on the counter to kick-start gluten development.
• Let the dough rest in the bowl for 10 minutes, then perform one set of stretch-and-folds (or coil folds; see notes).
• Every 30 minutes for the next 2 hours, repeat one more set of folds (total of 4).
• Cover and ferment in a warm spot (around 25 °C/77 °F) for 2–4 hours, until the dough has risen about 50%.

Pre-Shape

• Gently turn the dough out onto a lightly floured surface and divide it into two equal pieces.
• Take one piece and pat it into a rough square. Fold each corner into the center to form a parcel.
• Flip it seam-side down, cup it between your hands, and roll in small circles on the bench until a smooth ball forms.
• Place each ball on the floured surface, cover with a tea towel, and rest for 30 minutes until slightly puffed and passing the poke test (a gentle press leaves a slow-closing indentation).

Shaping

• Working one ball at a time, place it seam-side up on a floured board and gently press into a horizontal rectangle.
• Fold the top third down to the center, seal with your fingertips, rotate 180°, and repeat.
• Starting at the top right corner, fold small flaps down in succession. Press with your palm heel and pull slightly to lengthen. Aim for a 30 cm (12″) log.
• Roll the log under your palms toward you, tapering the ends into classic baguette points.
• Transfer each loaf seam-side up into a baguette pan or between heavily floured kitchen towels (use the towel edges as “walls” if you don’t have a pan).
• Dust the tops generously with flour, cover and cold-proof in the refrigerator for 8–24 hours.

Baking

• Preheat your oven to 230 °C (450 °F) with a baking sheet or stone on the middle rack and an empty pan on the bottom.
• Remove the baguettes from the fridge.
• Dust a floured board, invert each loaf seam-side down onto it, and score at least three angled slashes with a razor or sharp blade.
• Dust the baking sheet or stone with flour, then slide the loaves onto it. Pour around 1 cm of water or a few ice cubes into the bottom pan to generate steam.
• Bake 30–35 minutes, until deeply golden. Be cautious when opening the door because steam will rush out.
• Cool on a wire rack before slicing (or tear into that crisp crust while still warm!).