Makes 1 large round loaf
If your starter is mature and has been refreshed and cold-stored within the last week as described here, step 1 can be skipped and the levain can be used straight from the fridge in step 2. King Arthur all-purpose flour works best here; if unavailable, substitute bread flour. If only low-protein all purpose flour such as Gold Medal or Pillsbury is available, add 8 grams (1 tablespoon) vital wheat gluten to the flour and stir well. For best results, weigh your ingredients. When making the dough, be sure to save the leftover starter for future use. Since the dough requires a 12-hour room temperature proof in step 4, it is easiest to start the dough early in the morning or late in the evening. If you don't have a banneton, substitute a colander lined with a linen towel. The recipe can be made in any cast-iron Dutch oven from 5 to 8 quarts in size. Do not wait until the oven has preheated to start your timer or the bread will burn.
28g (3 tablespoons) King Arthur all-purpose flour
28g (2 tablespoons) cool (70 degrees F) water
14g mature starter
390g (1 2/3 cups) cool (70 degrees F) water, divided
65g levain (from above)
550g (3 7/8 cups) King Arthur all-purpose flour
2 teaspoons (11g) table salt
Vegetable oil spray
1. FOR LEVAIN: Combine flour, water, and starter in small bowl and stir with wooden spoon until uniform. Cover with plastic wrap and let sit until doubled in volume, 3 to 5 hours. Transfer to refrigerator and use within 7 days.
2. FOR DOUGH: Set 1 tablespoon of water aside. Whisk remaining water and levain together in large bowl (save remaining levain for future use or discard). Add flour, and, using wooden spoon, stir mixture, scraping up dry flour from bottom of bowl until dough comes together and no dry flour remains. Cover with plastic wrap and let rest at room temperature for 30 minutes.
3. Sprinkle salt and remaining water over top of dough, then, using wet hands, knead dough by hand in bowl until uniform (dough will remain slightly shaggy). Cover with plastic wrap and let rest at room temperature for 30 minutes.
4. Using wet hands, holding edge of dough with your fingertips, fold dough over itself by gently lifting and folding edge of dough toward center. Turn bowl 45 degrees; fold again. Turn bowl and fold dough 6 more times (total of 8 folds). Cover bowl with plastic wrap and let sit at room temperature until bubbly and domed, about 12 hours.
5. Dust top of dough lightly with flour, then invert dough floured-side down onto lightly floured counter. Gently press dough into 8-inch disk, then fold edges toward middle to form round. Cover loosely with plastic or inverted bowl and let rest for 30 minutes. Meanwhile, line banneton with large linen or cotton dish towel and dust liberally with flour, rye flour, or a 50/50 mixture of white flour and rice flour. Repeat pressing and folding of dough to form round, then place dough seam side down on counter and form into tight round. (To round, set dough on unfloured counter. Loosely cup your hands around dough and, without applying pressure to dough, move your hands in small circular motions. Tackiness of dough against counter and circular motion should work dough into smooth, even ball, but if dough sticks to your hands, lightly dust your fingers with flour.)
6. Place dough seam side up on floured towel and loosely fold edges of towel over dough to enclose. Place banneton in large plastic bag and tie or fold under to fully enclose. Let rest at room temperature for 1 hour, then refrigerate for 12 to 24 hours.
7. Lay 12 by 12-inch sheet of parchment paper on counter and spray with oil spray. Remove colander from plastic bag, unfold edges of towel, and dust top of loaf with flour. Lay parchment sprayed side down over loaf, then invert banneton onto counter. Remove banneton and towel.
8. Adjust oven rack to middle position. Lightly flour top of dough and, using razor blade or sharp knife, make one 6-inch-long, 1/2-inch-deep slit along top of dough. Pick up dough by lifting parchment edges and lower into heavy-bottomed Dutch oven. Cover pot and place in oven. Heat oven to 425 degrees. Bake bread for 30 minutes.
9. Remove lid and continue to bake until loaf is deep brown, 15 to 30 minutes longer. Carefully remove bread from pot; transfer to wire rack and let cool completely before slicing, at least 2 hours.