Directions

1. Whisk together lukewarm water and yeast in the bowl of a stand mixer. Let stand until yeast is fully dissolved, about 3 minutes.
2. Add flour to mixer bowl; beat with a stand mixer fitted with a dough hook attachment on low speed until combined and a rough dough forms, about 4 minutes. Add salt; beat on medium-low speed until an elastic dough forms, about 3 minutes. Transfer dough to a large bowl or plastic container lightly greased with oil; cover and let rest in a warm (75°F) place for 30 minutes.
3. Loosen edges of dough from bowl using a flexible dough scraper. With damp hands, grab top edge of dough (farthest away from you); gently stretch, lift, and fold dough over itself towards you, pressing it into surface of dough. Grab bottom edge of dough (closest to you); gently stretch, lift, and fold dough over itself away from you, pressing it into surface of dough. Turn bowl 90 degrees (quarter-turn), and repeat stretching and folding process once more. Using the bowl scraper to assist you, gently turn dough over so the bottom (smooth) side is facing up. Cover and let rest in a warm (75°F) place for 30 minutes. Repeat folding process 2 more times at 30-minute intervals. After third and final fold, cover dough, and let rest in a warm (75°F) place until dough is nearly doubled in size and some small bubbles start to peek through surface, 30 to 60 more minutes.
4. Cover dough, and chill in refrigerator at least 12 hours or up to 48 hours. (Dough will continue fermenting and developing flavor.)
5. Remove dough from refrigerator. (Dough should be doubled in volume and there should be some bubbles on surface. If not, let dough sit at room temperature until some bubbles form before proceeding, 30 to 45 minutes.) Uncover and use a flexible dough scraper to loosen dough from edges of bowl. Gently invert dough onto a lightly floured surface. Divide dough evenly into 3 portions (about 280 grams or 10 ounces each).
6. Preshape dough: Working with 1 dough portion at a time, gently stretch dough into a rough 8- x 5-inch rectangular shape (shape does not need to be perfect). Starting from 1 short side, gently roll dough, jelly roll style, into a loose cylinder (about 6 inches long). Place dough cylinder, seam side down, on a lightly floured surface. Repeat preshaping process with remaining 2 dough portions. Cover with a clean towel, and let rest at room temperature until dough is relaxed, 30 to 45 minutes.
7. Meanwhile, preheat oven to 500℉ with a large baking stone on center rack and a large cast iron skillet on bottom rack. Let oven preheat for at least 1 hour.
8. Shape dough: Working with 1 dough cylinder at a time, gently press cylinder down to form a 7- x 4-inch rectangular shape with long sides parallel to you. Fold top of dough two-thirds of the way down, pressing lightly to seal. Rotate dough 180 degrees so folded edge is closest to you. Fold new top of dough two-thirds of the way down, pressing lightly to seal. Using your nondominant hand and starting on 1 short end of dough, place your thumb on center midline of dough. Use fingers on your dominant hand to lift top of dough and fold it in half, over your thumb. Use the heel of your dominant hand to press and seal seam. Repeat this motion, moving from 1 end of dough to the other, forming an elongated cylinder. Using both hands, gently roll dough backwards and forwards into a 15-inch-long rope, moving hands outwards from center of dough with increasing pressure to create slightly tapered ends. (Dough should be about 15 inches long and about 1 1/2 inches in diameter.)
9. Using 2 hands, gently lift dough, and transfer, seam side up, to a well-floured couche. Loosely cover with opposite end of couche while repeating shaping process with second dough portion. Transfer second shaped dough, seam side up, to couche, pleating couche in between 2 dough portions to create a “wall” supporting and separating them. Loosely cover with opposite end of couche while shaping third dough portion. Transfer third shaped dough to couche, seam side up. Create a final pleat, and cover all 3 shaped dough portions with opposite end of couche.
10. Let dough stand at room temperature until dough is about 50% increased in volume (not doubled) and dough springs back slowly when indented, 30 to 45 minutes.
11. When dough is proofed, gently roll dough cylinders, 1 at a time, onto a baguette transfer peel. Transfer dough to a rimless baking sheet lined with parchment paper, gently rolling dough off transfer peel and onto parchment paper, seam side down. Use peel to gently straighten dough if necessary. Repeat with remaining dough cylinders, placing them seam sides down and at least 2 inches apart on same sheet of parchment paper.
12. Score dough using a lame or razor blade: Holding the lame at a shallow angle (about 20 degrees), score 5 diagonal slashes along centerline of dough cylinder, with each subsequent slash overlapping the previous by about 20%.
13. Quickly slide dough on parchment paper onto preheated baking stone and carefully pour boiling water into preheated skillet to create steam. Quickly close oven door to trap steam, and bake in preheated oven 10 minutes. Carefully remove skillet, and reduce oven temperature to 450°F. Continue baking until crust is golden and baguettes are cooked (they should sound hollow when tapped on bottom), 12 to 14 minutes. Turn oven off, and open oven door slightly. Let baguettes cool in oven with door ajar for 15 minutes. Transfer baguettes to a wire rack, and let cool at least 15 minutes. Serve warm, or cool completely on wire rack, about 30 minutes.