Make the poolish: The morning of the day before you plan to bake the baguettes, combine the ⅛ teaspoon yeast and 60 grams/¼ cup water (at 75 degrees to 80 degrees) in a plastic lidded container (preferably quart-size, or anything with straight sides and a similar capacity) and stir briefly to dissolve the yeast. Add the flour and mix, scraping along the sides of the container, until thoroughly combined and you have a thick, sticky paste. Smooth the surface, cover and mark the height of the mixture on the side of the container using a tape or rubber band. Let sit at warm room temperature (preferably around 75 degrees) until it triples in volume, and the surface, which should teem with fine bubbles, is slightly domed, 6 to 7 hours (but possibly more or less depending on the ambient temperature).

Mix the dough: When the poolish is ready, scrape it into a large bowl and add 375 grams (a scant 1¾ cups) water, at 75 degrees to 80 degrees, and ½ teaspoon yeast. Stir to dissolve the yeast and as much of the poolish as you can, then add the flour and salt. Using a bench scraper or flexible spatula, mix, making sure to scrape the bottom and sides of the bowl, until all of the flour is moistened and you have a soft, shaggy dough.

Holding the bowl stable with one hand, use your other hand to knead the dough, grasping a handful at the edge of the mass, pulling it upward and pressing it back into the center. Continue to knead, rotating the bowl as you work, until the dough has firmed up slightly and starts to give you some resistance, about 5 minutes. At this point, the dough will still be sticky and textured but should somewhat hold its shape. Scrape down the sides of the bowl, then, scrape all the dough into a straight-sided lidded container with a 4-quart capacity, if available to you, coated with a bit of water or very thin layer of neutral oil to prevent sticking. If not, scrape the dough into a single mass in the bowl. Cover the container or bowl and use a piece of tape to mark the height of the dough on the side.

Bulk fermentation: Let the dough sit at warm room temperature (preferably around 75 degrees), for 1 hour, then give it a series of folds: Uncover the dough and, using damp hands, scoop underneath the dough along one side of the container or bowl with both hands and slowly lift it up and out of the container or bowl to stretch it, then lower it back down so it folds onto itself. Repeat this folding process three more times, rotating the container or bowl 90 degrees each time and rewetting your hands to prevent sticking. (You’ll notice the dough will now feel stronger and smoother and hold its shape better.)

Cover the dough again and let it sit, repeating this series of 4 folds every 30 minutes, until the dough is smooth and elastic, has grown about 50 percent in volume and has lots of bubbles beneath the surface, 1 to 2 hours. Give dough a final series of folds, then cover and refrigerate for 12 to 24 hours.

Finish bulk fermentation: On Day 2, remove the dough from the refrigerator and take a look at it. If it hasn’t doubled from its original size during its rest in the refrigerator, let it sit out at room temperature until it reaches this point, 1 to 2 hours. If it looks doubled right out of the fridge, proceed to the next step.

Divide dough: Lightly dust your work surface with flour, then gently scrape the dough onto the floured surface. Use a bowl scraper, bench scraper or knife to divide the dough into 3 equal portions. (To ensure even loaves, use a scale; each should weigh about 330 grams.)

Preshape the dough: Very lightly flour the surface of each piece of dough. Working one piece at a time and, using floured hands, gently pat the dough into a square measuring about 6 inches across. Working from the side farthest from you, roll the dough toward you into a tight cylinder. Place the cylinders on the floured work surface seam-sides down, leaving several inches of space between them, and cover with a clean kitchen towel. Let rest for 20 minutes.

Prepare the oven: While the dough is resting, arrange one oven rack in the center position and another in the lower third. Place a 20-inch-long baking stone on the middle rack and a large cast-iron skillet on the lower rack. Heat the oven to 500 degrees.

Prepare the cloth: Place a thick kitchen towel (or, if you have one, a linen couche) on a rimless baking sheet that’s at least 18 inches long (or, if you don’t have one, an upside-down rimmed baking sheet). Generously dust the towel with flour and set aside.

Shape the baguettes: Lightly flour the work surface, then use the scraper to quickly lift one of the cylinders and turn it over onto the floured work surface so it's seam side up on the floured surface. Very lightly dust the dough with flour and use floured hands to pat it down gently, popping any larger bubbles and flattening it into a rectangle with the short ends oriented to the left and right. Fold the long end opposite you down over the bottom half, leaving the lower third of the dough uncovered. Rotate the dough 180 degrees, then fold down the uncovered third of dough (the side farthest from you) so you have a long cylinder of dough with a seam running through the center. Starting at one end and working your way to the other, fold the dough in half lengthwise by bringing the top half down over the bottom and pressing firmly along the seam to seal. Throughout the shaping process, if the dough sticks to your hands or the surface, dust with just a bit more flour. Applying light downward pressure with both palms and starting in the center and working outward, roll out the dough to a length of 18 inches, doing your best to make it as even as possible and tapering the ends.

Transfer the shaped dough to the floured towel, placing it seam side up in the middle. Pleat the towel on either side of the dough to create a barrier, then repeat the shaping process with the 2 remaining portions of dough and place them on the floured towel on either side of the first so all 3 pieces are sitting snugly next to one another. Fold the ends of the towel up and over the dough to cover. (Use a second towel if necessary.)

Proof the baguettes: Let the baguettes sit at warm room temperature (preferably around 75 degrees) until they’re about 50 percent expanded in size, 30 to 60 minutes. To check if they’re proofed, poke the dough gently: If it takes a couple of seconds to spring back and holds a slight indentation, it’s proofed. If the dough springs back quickly, it’s not quite ready, so let it go longer.

Boil water for steam and prepare the parchment: While the dough is proofing, bring 1 cup water to a boil in a kettle or saucepan, then set aside. Place a piece of parchment paper about the size of your baking stone over a rimless baking sheet or a thin wooden board and dust lightly with semolina flour.

Transfer the loaves: Uncover the dough and pull on the ends of the towel to flatten the pleats, separating the loaves. Lightly dust the tops of the dough with flour. Working one at a time and using the towel to help you, flip one of the outer baguettes onto a thin wooden board measuring about 20 inches long and 4 inches wide (also called a baguette transfer peel; you can also have one cut at your local hardware store) so it’s seam side down, then slide it gently onto the parchment paper, orienting it lengthwise. Repeat with the remaining loaves, spacing them out evenly on the parchment. (If the dough is covered with lots of flour from the towel, gently brush it off with a pastry brush, then brush it from the parchment.)

Score the loaves: Use a razor blade or bread lame to score each baguette 5 times at a diagonal, angled down the middle of the loaf and parallel to one another. Try to slash deeply, confidently and quickly, as the blade will want to drag through the soft dough. For the best shape, hold the blade at about a 30-degree angle, rather than cutting straight down into the dough.

Carefully slide the loaves and parchment off of the baking sheet or board and onto the heated baking stone. Slide the lower rack out a couple of inches and pour the 1 cup boiled water into the cast-iron skillet and immediately close the door. (The water will instantly turn to steam, so protect your arms and work quickly so it doesn’t escape.) Bake for 10 minutes, then open the oven briefly to let out any steam. (Some ovens hold steam better than others, so there may not be any left at that point.)

Reduce the oven temperature to 450 degrees and bake until the loaves are deeply browned, another 10 to 15 minutes. Use a pair of tongs to remove the baguettes from the oven and let cool.