STARTER
75 grams (1/2 c + 2 tbsp) white rye flour
50 grams (1/4 c + 21/2 tbsp) dark rye flour
1 gram (generous 1/4 tsp) instant yeast
125 grams (1/2 c + 1 tsp) water at about 60°F (15°C)
DOUGH
425 grams (3 c + 21/2 tsp) white flour, plus additional as needed for working with the dough
75 grams medium (1/2 c + 11/2 tsp) whole wheat flour
15 grams (21/2 tsp) fine sea salt
1 gram (generous 1/4 tsp) instant yeast
365 grams (11/2 c + 1 tsp) water at about 60°F (15°C)
Dusting Mixture, for the lined proofing basket and the shaped loaf
FOR THE STARTER
1 Stir together the white and dark rye flours in a medium storage container. Sprinkle the yeast into the water, stir to mix, and pour over the flour. 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 11 to 15 hours. The starter will be at its peak at around 13 hours.
FOR THE DOUGH
1 Stir together the white and whole wheat flours, 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. Using a wooden spoon, break the starter up to distribute it in the water.
3 Add the flour mixture, reserving about one-sixth 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 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 16 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 45 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 45 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 45 minutes.
7 For the third and final stretch and fold, once again 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.
8 Line a 9-inch (23 cm) proofing basket or bowl with a clean kitchen towel and dust the towel fairly generously with the dusting mixture.
9 Lightly dust the work surface and your hands with flour and shape the dough into a round (see Shaping a Round Loaf). Dust the sides and top of the dough with the dusting mixture, fold the edges of the towel over the top, and let rest at room temperature for 1 hour.
10 Transfer the basket to the refrigerator and chill for 14 to 18 hours.
11 Position an oven rack in the lower third of the oven. Place a covered 6-quart (5.7 L), 10-inch (25 cm) round cast-iron Dutch oven on the rack. Preheat the oven to 500°F (260°C). Remove the basket of dough from the refrigerator and let it sit at room temperature while you allow the oven to preheat for about 1 hour.
12 Using heavy-duty oven mitts or potholders, remove the Dutch oven, place it on a heatproof surface, and remove the lid.
13 Using the kitchen towel, lift and gently ease the dough out of the basket and onto a baking peel, seam-side down. Then carefully transfer it into the pot (the Dutch oven will be very hot). Score the top of the dough (see Scoring), cover the pot, and return it to the oven. Lower the oven temperature to 460°F (240°C) and bake for 30 minutes.
14 Rotate the Dutch oven and remove the lid. The loaf will already be a rich golden brown. Continue baking, uncovered, until the surface is a deep, rich brown, with some spots along the score being even slightly darker (bien cuit), about 20 minutes longer.
15 Loosen the edges of the loaf with a long handled spoon and then with the help of the spoon lift out of the pot onto a cooling rack. When the bottom of the loaf is tapped, it should sound hollow. If not, return it to the oven and bake directly on the rack for 5 minutes longer.
16 Let the bread cool completely before slicing and eating, at least 4 hours but preferably 8 to 24 hours.
For most doughs—with the exception of sweeter, enriched loaves like the White Pullman Loaf—I dust the kitchen towel, linen liner, or proofing basket, and the top and sides of the dough with a blend of semolina flour and white flour. The semolina, which is slightly coarser, helps keep the dough from sticking. Don’t use this mixture during mixing, rolling and tucking, stretching and folding, or shaping, as the semolina will change the quality of the dough incorporated into it.
To make the Dusting Mixture, combine one part fine semolina flour with five parts white flour. If you bake often, mix up a large batch and keep it on hand.