Day before making the dough

Make the leaven: Discard all but 1 tablespoon of the starter. Feed the remaining starter with 200 grams of warm water, 100 grams of whole wheat flour, and 100 grams of bread flour. Let the mixture rise overnight at room temperature. When it’s ready, the leaven should have risen slightly, float in room temperature water (test a small piece; you can still use this piece in the final dough), and smell like sweet sour pancake batter.

On the day of baking

Make the Dough: Pour 700 grams warm water into a large mixing bowl. Add 200 grams leaven. Stir to disperse. (Store the rest of leaven for future use.) Add flours and mix dough with your hands until no bits of dry flour remain. Set aside for autolyse in a cool, dark place for 35 minutes. Add salt and remaining 50 grams warm water.

Transfer to large container so that you can fold the dough in between. Set aside for fermentation for 3-4 hours. Make sure fold the dough every 30 minutes intervals for first 2 ½ hours and then rest fold at 1 hour interval. To do a fold, dip 1 hand in water to prevent sticking. Grab the underside of the dough, stretch it out, and fold it back over itself. Rotate container one-quarter turn, and repeat. Do this 2 or 3 times for each fold. After the 3 hours, the dough should feel aerated and softer, and you will see a 20 to 30 percent increase in volume. If not, continue bulk fermentation for 30 minutes to 1 hour more. This will help to develop flavor and strength. (The rise is temperature sensitive; as a rule, warmer dough ferments faster. Robertson tries to maintain the dough at 78 degrees to 82 degrees to accomplish the bulk fermentation in 3 to 4 hours.)

Pull dough out of container using a dough spatula. Transfer to a floured surface. Lightly dust dough with flour, and cut into 2 pieces using dough scraper. Work each piece into a round using scraper and 1 hand. At first you will dough is slightly attached to sides as tension builds, in the end, the dough should have a taut, smooth surface.

Dust tops of rounds with flour, cover with a kitchen towel, and let rest on the work surface for 20 to 30 minutes. Slip the dough scraper under each to lift it, being careful to maintain the round shape. Flip rounds floured side down.

Line 2 medium baskets or bowls with clean kitchen towels; generously dust with flour. Using the dough scraper, transfer each round to a basket, smooth side down, with seam centered and facing up. Let rest at room temperature (75 degrees to 80 degrees), covered with towels for 2 to 4 hours before baking.

Half hour before you are ready to bake the bread, preheat oven to 500 degrees, with rack in lowest position, and warm a 9 ½-inch round or an 11-inch oval Dutch oven (or a heavy ovenproof pot with a tight-fitting lid).

Turn out 1 round into heated Dutch oven (it may stick to towel slightly). Score top twice using a razor blade or a sharp knife. Cover with lid. Return to oven, and reduce oven temperature to 450 degrees. Bake for 20 minutes.

Carefully remove lid (a cloud of steam will be released). Bake until crust is deep golden brown, 20 to 25 minutes more or until it register internal temperature of 205F.

Transfer loaf to a wire rack. It will feel light and sound hollow when tapped. Let cool.

To bake the second loaf, raise oven temperature to 500 degrees, wipe out Dutch oven with a dry kitchen towel, and reheat with lid for 10 minutes. Then transfer the second round and reduce the oven temperature to 450F and continue to bake as you did the first one.