Step 1

At 9:15 p.m. PREPARE LEVAIN: Place a clean starter jar on a kitchen scale. Tare the weight so it reads “0”, then to the jar add 50g mature starter, 200g whole wheat flour and 200g distilled water at room temperature. Stir the mixture vigorously until no dry bits of flour remain, then cover the jar loosely with a lid. Store in a warm place (such as the oven with the light on) for approximately 10-12 hours.

Step 2

At 8:30 a.m. (next day) PREPARE AUTOLYSE: The next morning, place a medium to large mixing bowl on a kitchen scale. Tare the weight so it reads “0”, then to the bowl add 250g levain and 750g distilled water at room temperature. Stir the mixture until the levain is completely dissolved. Add 800g bread flour and 200g whole wheat flour. Mix with your hands until mixture is completely incorporated. Cover bowl with plastic wrap and place in a warm place (such as the oven with the light on) for 50 minutes.

Step 3

At 9:20 a.m. FINISH THE DOUGH MIX: To the mixing bowl add 20g fine sea salt and remaining 50g distilled water (at temperature calculated as described in post to achieve final dough temperature of 78 degrees F). Mix with your hands until mixture is completely incorporated. Cover bowl with plastic wrap and place in a warm place (such as the oven with the light on) for 30 minutes.

Step 4

At 10 a.m. BULK FERMENTATION: After 30 minutes have elapsed, perform the first set of turns (see post for full description on how to perform a set of turns). Cover the bowl and return it to its warm place.

Step 5

At 10:30 a.m. Perform second set of turns. Cover and return to warm place.

Step 6

At 11 a.m. Perform third set of turns. Cover and return to warm place.

Step 7

At 11:30 a.m. Perform fourth set of turns. Cover and return to warm place.

Step 8

At 12 p.m. Perform fifth set of turns. Cover and return to warm place.

Step 9

At 12:30 p.m. Perform sixth and final set of turns. Cover and return to warm place to finish bulk fermentation, untouched.

Step 10

At 2:00 p.m. PRESHAPE: Gently transfer dough to a well-floured surface. Using a well-floured bench scraper or knife, divide dough into two equal pieces. Use floured hands to gently but quickly shape each piece of dough into a tight round (see post for full description on preshape). Cover dough with bowls and let rest on counter for 30 minutes.

Step 11

At 2:30 p.m. SHAPE AND PROOF: Lightly dampen and dust two banneton baskets or linen-lined bowls with white rice flour. Remove bowls from dough. Shape dough into boule (see post for full description on how to shape into a boule). Carefully transfer dough to one prepared basket. Repeat with second dough.

Step 12

Cover each basket with a plastic bag; use a clip to seal bag. Let dough rest in bags at room temperature 20 minutes, then transfer to refrigerator for an overnight proof.

Step 13

At 7:30 a.m. (next day) PREHEAT: Place an oven rack on bottom third of oven. Place deep side of combo cooker facing down on one side of oven rack; place shallow side of combo cooker facing up on other side. Preheat oven to 510 degrees F for 1 hour.

Step 14

Just before baking, remove one dough from refrigerator and plastic bag. Place a sheet of parchment paper and a cutting board on top of basket. Carefully invert basket with cutting board so dough lands on parchment paper. Remove basket. Use a bread lame to score top of dough.

Step 15

At 8:30 a.m. BAKE: Using oven mitts, carefully slide dough on parchment paper to shallow side of combo cooker. Place deep side of combo cooker on top to seal. Reduce oven temperature to 500 degrees F. Bake covered 20 minutes. Reduce oven temperature to 450 degrees F. Bake covered another 10 minutes. Using oven mitts, remove top of combo cooker and return to oven rack in oven to keep hot. Bake bread uncovered another 25-30 minutes until a deep golden brown (an instant thermometer should read an internal temperature of approximately 210 degrees F). Transfer bread to a cooling rack to cool completely, about 1 hour 30 minutes. Repeat with second loaf.