• Begin by accurately measuring the flours either by weighing or using the spoon-and-sweep method.

Day 1:

• Start preparing the dough early in the morning. In a large mixing bowl, combine the ripe sourdough starter, bread flour, whole wheat flour, salt, honey, sesame seeds, and warm water. Mix until there are no visible dry patches. With moistened hands, lightly knead the dough by pressing it against the bowl's side until it becomes slightly smoother and tacky to the touch.
• Cover the dough and let it rest for 15 minutes. Perform a bowl fold by using wet hands to lift a section of the dough, stretch it up, and fold it back into the center. Rotate the bowl and repeat this stretch-and-fold motion 8 to 12 times until the dough offers resistance.
• Cover again and rest for another 15 minutes. Conduct a second bowl fold, but this time only stretch 6 to 8 times until the dough tightens and resists further stretching.
• After another 15-minute rest, perform a third bowl fold. Rest once more for 15 minutes and then proceed with the fourth and final bowl fold, folding until the dough resists.
• Flip the dough so that the smooth side is facing upward. Cup your hand around the dough, gently tightening it by pulling towards the bottom to build surface tension. Transfer the dough into a large, preferably clear container. Mark the starting height of the dough on the container to monitor its rise.
• Cover the dough and allow it to ferment at room temperature for 7 to 11 hours until it appears marshmallowy and doubles in volume. Keep an eye on its texture rather than strictly relying on time—warmer environments or active starters will shorten the rise time, while cooler temperatures may extend it.
• Once fully risen, gently tip the dough onto a lightly floured work surface. Use a bench scraper or knife to divide the dough into two equal portions, approximately 930g each.
• Pat each piece gently to expel any large air pockets, then preshape into a round shape. Cover the rounds and allow them to relax for 15 minutes.
• Shape each dough ball into a boule or bâtard. Lightly dust two 9" x 3" round or oval bannetons with flour—using less flour than usual due to the seed crust.
• Scatter the sesame seeds for the crust onto a rimmed baking sheet or a sheet of parchment paper. Dampen a clean kitchen towel thoroughly, then wring it out until damp but not dripping. Roll each shaped loaf lightly over the towel to moisten the surface, then roll it through the sesame seeds to coat the top and sides thoroughly.
• Place the seeded loaves seam-side up into the prepared bannetons. If the dough doubled within 7 to 8 hours during bulk fermentation, transfer the loaves directly to the refrigerator for a slow proof. If bulk fermentation took closer to 11 hours, let the loaves rise at room temperature for 1 additional hour before chilling. At the end of this slow final rise, the dough should feel light and a gentle fingerprint should leave an impression without springing back immediately.

Day 2:

• Preheat your oven to 475°F. Position a baking stone or steel on the middle rack and place an empty cast iron skillet or a tray filled with lava rocks on the rack beneath it. For optimal steam circulation, try to arrange the stone and skillet so the skillet isn't directly underneath the stone.
• Invert the loaves carefully onto parchment paper. Using a baker’s lame or a sharp razor, score the tops of the loaves with clean, confident slashes.
• Load the loaves into the oven, still on the parchment, placing them side-by-side on the baking stone or steel. Immediately pour about 1 cup (227g) of warm water into the hot skillet to generate a burst of steam.
• Bake the loaves at 475°F for 25 minutes. Then lower the oven temperature to 450°F and continue baking for another 20 minutes, or until the loaves are richly browned and the crust feels firm to the tap.
• Remove the loaves from the oven and allow them to cool completely on a wire rack before slicing.

Storage Information:

• Store the cooled loaves at room temperature, lightly wrapped in a cloth or paper bag for up to two days. For longer storage, freeze the loaves and reheat when needed to restore freshness.