Prepare the levain – 9:00 p.m. (the night before mixing)

Mix the ingredients in the chart above in a tall jar, covered at a warm temperature, 74-76°F (23-24°C), to ripen for 12 to 14 hours.

Prepare the tangzhong – 9:10 a.m. (the day of mixing)

In a medium saucepan over medium-low heat, combine the tangzhong ingredients. Cook, whisking continuously, until the mixture thickens and becomes a paste (it should look like mashed potatoes), 5 to 7 minutes.

Mix – 9:30 a.m.

To the bowl of a stand mixer fitted with the dough hook, add flour, tangzhong, milk, sugar, water, salt, and ripe levain. Mix on low speed for 1-2 minutes until combined, with no dry bits remaining.

Bulk Fermentation – 10:00 a.m. to 1:30 p.m. (3 ½ hours)

At a warm room temperature, 74-76°F (23-24°C), bulk fermentation should take about 3 ½ hours.

Divide and Shape – 1:30 p.m.

Line two baking sheets with parchment paper. Lightly flour your work surface, and using a bowl scraper, gently scoop the dough out to the floured area. Lightly flour the top of the dough and divide it into 10 (135-gram) portions.

Proof – 2:00 p.m. to 4:30 p.m.

Cover the baking sheets with reusable plastic or snap-on baking sheet covers and let the dough proof for 2 ½ hours.

Bake – 4:30 p.m. (preheat oven at 4:00 p.m.)

30 minutes before baking, preheat oven to 450°F (232°C) with racks in the upper and lower thirds. For the egg wash, whisk 1 egg and 1 tablespoon of milk until frothy. Uncover baking sheets and brush with egg wash. Sprinkle sesame seeds if desired. Bake for 15 minutes. Rotate pans, reduce temperature to 425°F (220°C), and bake for another 5-10 minutes until well-colored.