STARTER
200 grams (1 c + 3 tbsp) medium-grind cornmeal
100 grams (1/2 c + 31/2 tbsp) white flour
0.2 gram (pinch) instant yeast
260 grams (1 c + 11/2 tbsp) water at about 60°F (15°C)
DOUGH
380 grams (21/2 c + 3 tbsp) white flour, plus additional as needed for working with the dough
120 grams (3/4 c) medium-grind cornmeal
30 grams (21/2 tbsp) granulated sugar
15 grams (21/2 tsp) fine sea salt
1 gram (generous 1/4 tsp) instant yeast
150 grams (1/2 c + 2 tbsp) water at about 60°F (15°C)
60 grams (1/4 c) bourbon
25 grams (13/4 tbsp) unsalted butter, at room temperature
Dusting Mixture, for the linen liner and shaped loaves
FOR THE STARTER
1 Stir together the cornmeal and white flour in a medium storage container. Sprinkle the yeast into the water, stir to mix, and pour over the cornmeal mixture. Mix with your fingers, pressing the mixture into the sides, bottom, and corners until all of the flour is wet and fully incorporated. Cover the container and let sit at room temperature for 10 to 14 hours. The starter will be at its peak at around 12 hours.
FOR THE DOUGH
1 Stir together the white flour, cornmeal, sugar, salt, and yeast in a medium bowl.
2 Pour about one-third of the water around the edges of the starter to release it from the sides of the container. Transfer the starter and water to an extra-large bowl along with the remaining water and the bourbon. Using a wooden spoon, break the starter up to distribute it in the liquid.
3 Add the flour mixture, reserving about one-sixth of it along the edge of the bowl (see Mixing). Continue to mix with the spoon until most of the dry ingredients have been combined with the starter mixture. Switch to a plastic bowl scraper and continue to mix until incorporated. At this point the dough will be just slightly sticky to the touch.
4 Push the dough to one side of the bowl. Roll and tuck the dough (see Rolling and Tucking), adding the reserved flour mixture and a small amount of additional flour to the bowl and your hands as needed. Continue rolling and tucking until the dough feels stronger and begins to resist any further rolling, about 8 times. Then, with cupped hands, tuck the sides under toward the center. Place the dough, seam-side down, in a clean bowl, cover the top of the bowl with a clean kitchen towel, and let rest at room temperature for 30 minutes.
5 For the first stretch and fold (see Stretching and Folding), lightly dust the work surface and your hands with flour. Using the plastic bowl scraper, release the dough from the bowl and set it, seam-side down, on the work surface. Gently stretch it into a roughly rectangular shape. Fold the dough in thirds from top to bottom and then from left to right. With cupped hands, tuck the sides under toward the center. Place the dough in the bowl, seam-side down, cover the bowl with the towel, and let rest for 30 minutes.
6 For the second stretch and fold, repeat the steps for the first stretch and fold, then return the dough to the bowl, cover with the towel, and let rest for 30 minutes.
7 For the third stretch and fold, gently stretch the dough into a rectangle. Pinch the butter into pieces, distributing them over the top of the dough. Using your fingers or a spatula, spread the butter across the surface of the dough. (For photos of the following process, see Incorporating Add-Ins.) Roll up the dough tightly from the end closest to you; at the end of the roll the dough will be seam-side down. Turn it over, seam-side up, and gently press on the seam to flatten the dough slightly. Fold in thirds from left to right and then do 4 or 5 roll and tuck sequences to incorporate the butter. Turn the dough seam-side down and tuck the sides under toward the center. Return the dough to the bowl, cover with the towel, and let rest for 30 minutes.
8 For the fourth and final stretch and fold, repeat the steps for the first stretch and fold, then return the dough to the bowl, cover with the towel, and let rest for 20 minutes.
9 Line a half sheet pan with a linen liner and dust fairly generously with the dusting mixture.
10 Lightly dust the work surface and your hands with flour. Using a bench scraper, divide the dough into 2 equal pieces. Press each into a 7-inch (18 cm) square, then roll into a loose tube about 7 inches (18 cm) long (see Shaping a Tube or Oval Loaf). Let rest for 5 minutes. Press each piece out and then shape into a very tight tube 9 to 10 inches (23 to 25 cm) long. Using a bench scraper, make 3 to 5 cuts on the diagonal down the loaf. Then, make 3 to 5 cuts in the opposite direction, crossing the first set of cuts, to make diamonds (see the photo here).
11 Transfer to the lined pan, cut-side down, positioning the loaves lengthwise. Dust the top and sides of the dough with flour. Fold the linen to create support walls on both sides of each loaf, then fold any extra length of the linen liner over the top or cover with a kitchen towel. Transfer the pan to the refrigerator and chill for 16 to 22 hours.
12 Set up the oven with a baking stone and a cast-iron skillet for steam (see Baking Stones and Steam, then preheat the oven to 480°F (250°C).
13 Using the linen liner, lift and gently flip the loaves off the pan and onto a transfer peel cut-side up. Slide the loaves, still cut-side up, onto a dusted baking peel (see Using a Transfer Peel and Baking Peel). Working quickly but carefully, transfer the loaves to the stone using heavy-duty oven mitts or potholders. Pull out the hot skillet, add about 3 cups of ice cubes, then slide it back in and close the oven door. Immediately lower the oven temperature to 440°F (225°C). Bake, switching the positions of the loaves about two-thirds of the way through baking, until the surface is a deep, rich brown, with some spots a long the scores being very dark (bien cuit), about 28 minutes.
14 Using the baking peel, transfer the loaves to a cooling rack. When the bottoms of the loaves are tapped, they should sound hollow. If not, return to the stone and bake for 5 minutes longer.
15 Let the bread cool completely before slicing and eating, at least 4 hours but preferably 8 to 24 hours.
