Step 1

– 9:00 p.m. (the night before mixing)Mix the levain ingredients in a jar and leave them covered at a warm temperature, 74-76°F (23-24°C), to ripen overnight.

Step 2

– 9:10 p.m. (the night before mixing)In a tall jar, combine the seed soaker ingredients, cover, and let sit until called for during mixing.

Step 3

– 8:00 a.m. (the day of mixing)In a small saucepan over medium-low heat, combine the tangzhong ingredients and whisk continuously until a thick paste forms. Scrape out to a plate to cool until called for during mixing.

Step 4

– 9:00 a.m.To the bowl of a stand mixer fitted with the dough hook attachment, add all of the main dough ingredients except the seed soaker. Mix on low speed for 1 to 2 minutes until the ingredients come together and no dry bits remain. If the dough is very dry, conservatively add a splash of water as needed to moisten it. Next, mix on medium speed for 5 minutes until the dough smooths and begins to cling slightly to the hook. Let the dough rest in the bowl for 5 minutes. Turn the mixer on medium speed and mix for 2 minutes until the dough gains more strength and clings once again to the dough hook. Add the seed soaker and mix on low speed just until the soaker is incorporated. Transfer the dough to a bulk fermentation container and cover.

Step 5

– 9:30 a.m. to 12:30 p.m. (3 hours)Give the dough 2 sets of stretches and folds during this time, at 30-minute intervals. After the second set, let the dough rest, covered, for the remainder of bulk fermentation. The dough is ready when it is smooth, puffy, and well-risen.

Step 6

– 12:30 p.m.Fill a small bowl with water and place it next to your work surface. Scrape the dough onto a clean counter and divide the dough into 2 equal pieces. Then, preshape each piece into a loose round. Let the dough rest, uncovered, for 30 minutes.

Step 7

– 1:10 p.m.Grease two 9 x 4 x 4-inch Pullman pans with a neutral-flavored oil. Shape each piece of dough into a long tube, top with sesame seeds if desired, and place them in their prepared pans.

Step 8

– 1:30 p.m. to 3:30 p.m. (about 2 hours)Put the pans in a large, reusable plastic bag and seal shut. Let the dough proof at warm temperature for about 2 hours. The dough is ready to bake when it is puffy to the touch and about 1/2 to 1-inch below the rim of the pan. If you see any large bubbles form on the surface, gently pat them down to disperse.

Step 9

– 3:30 p.m.Place an empty pan or pan with lava rocks on the bottom of the oven and preheat it to 425°F (220°C). Uncover the dough and slide the pans into the oven. Pour a cup of ice into the pan at the bottom of the oven and bake for 20 minutes. Then, reduce the oven temperature to 350°F (175°C), remove the steaming pan, and continue to bake for 25 to 30 minutes more. When done, the loaves should have an internal temperature of around 204°F (95°C), and the crust should be deeply colored. Remove from the oven, remove the loaves from their pans, and cool on a wire rack for at least 2 hours before slicing.