Step 1

Warm or cool the water to about 78°F (25°C). In a medium jar, mix the levain ingredients until well incorporated (this liquid levain will feel quite loose) and loosely cover. Store in a warm place for 12 hours.

Step 2

Place the 41 g white flour and 166 g milk in a medium saucepan set over medium-low heat. Cook, whisking constantly to ensure it does not burn, until the mixture thickens and becomes like a paste, 5 to 8 minutes. Be patient; the mixture won’t seem to do anything until it reaches a critical heat point. Remove the pan from the heat, spread the paste out on a small plate, and let cool completely.Tangzhong Timing: Be sure to make the tangzhong with plenty of time to cool to room temperature before mixing it into the dough. Alternatively, you can make the tangzhong the night before, let it cool for a few minutes on the counter, cover, and refrigerate it overnight. The next day, let it come to room temperature before mixing it into the dough.

Step 3

Check the levain for signs of readiness. It should be well aerated, risen, bubbly on top and at the sides, loose, and with a sharp sour aroma. If the levain is not showing these signs, let ferment 1 hour more and check again.

Step 4

Cut the butter into ½-inch-thick pats. Place the pats on a plate on the counter to warm to room temperature.

Step 5

Warm or cool the water to 78°F (25°C). To the bowl of a stand mixer fitted with the dough hook, add the tangzhong, flour, sugar, water, salt, and ripe levain. Mix on low speed for 1 to 2 minutes until combined. Increase the mixer speed to medium and mix for 5 to 6 minutes until the dough begins to cling to the dough hook, but it won’t completely clear the sides of the mixing bowl. Let the dough rest in the bowl, covered, for 10 minutes.

Step 6

Gently press a butter pat with your finger: Your finger should easily show an indentation in the butter but it should not be wet or melted. If the butter is too warm, place the butter in the freezer for 5 minutes and test again. Conversely, if the butter is too firm, microwave for 10 seconds to warm, then check again.

Step 7

With the mixer running on low speed, add the butter, one pat at a time, until absorbed into the dough, scraping down the sides of the bowl and the paddle as needed. Continue until all the butter is added, 5 to 8 minutes. Increase the mixer speed to medium and mix for 1 to 2 minutes more until the dough smooths out and clings to the dough hook once again. The dough will be silky smooth, elastic, and a little shiny. Transfer the dough to a container for bulk fermentation.

Step 8

Compare it to the desired dough temperature and record it as the final dough temperature. Cover the dough.

Step 9

Write down the current time as the start of bulk fermentation, set a timer for 30 minutes, and let the dough rest in a warm place.

Step 10

When your timer goes off, give the dough one set of stretches and folds. For each set, wet your hands. Grab one side of the dough and lift it up and over to the other side. Rotate the bowl 180 degrees and repeat. Then rotate the bowl a quarter turn and stretch and fold that side. Rotate the bowl 180 degrees again and finish with a stretch and fold on the last side. The dough should be folded up neatly. Cover and repeat these folds every 30 minutes for a total of 3 sets of stretches and folds.

Step 11

After the last set, cover the bowl and let the dough rest for the remainder of bulk fermentation, about 2 hours.

Step 12

At the end of bulk fermentation, the dough will have risen significantly; it may have bubbles on top and at the sides, it should look smoother and less shaggy, and at the edge of the dough where it meets the container, it should dome downward. If you wet a hand and gently tug on the surface of the dough, it will feel elastic and cohesive, resisting your pull. If you don’t see dough that’s airy, strong, and “alive,” leave it for another 15 minutes in bulk fermentation and check again.

Step 13

Uncover your bulk fermentation container and place the container in your refrigerator for 15 to 25 minutes. This time will firm and slightly chill the dough to make shaping easier.

Step 14

Liberally butter an 9-inch square baking pan with butter (even if your pan has a nonstick liner).

Step 15

Using a bowl scraper, gently scrape the dough onto a floured work surface. Dust the top of the dough with flour. Using a bench knife in one hand, and the other hand dusted with flour, divide the dough into 16 pieces of 70g each (you might have a small bit of scrap dough left over). Using your bench knife in your dominant hand, and other hand lightly floured, shape each Small Rounds, Buns, and Rolls, page 000, for more detail.) Place the pan inside an airtight reusable plastic bag and seal.

Step 16

Put the pan in a warm place to proof for 2 to 3 hours. The rolls are ready when they are well risen and are very soft to the touch. If you gently poke their surface, you shouldn’t feel any dense spots or tight areas; if you do, let proof 15 minutes more and check again.Overnight Proofing Option: Once the dough is shaped and in the baking pan, you can retard the rolls (proof overnight at cold temperature) until the next morning. Place the covered pan in the refrigerator overnight. The next morning, continue with the remaining steps of the recipe, adding 30 minutes to 1 hour to the final room temperature proof since the dough will need to warm to room temperature and then finish proofing.

Step 17

Place an oven rack in the middle position and preheat the oven to 425°F.

Step 18

Make the egg wash by whisking together the egg and 1 tablespoon milk. Using a pastry brush, brush the wash evenly on top of the dough. If desired, lightly sprinkle coarse sea salt over the rolls.

Step 19

Slide the baking pan into the oven and bake for 20 minutes. Rotate the pan 180 degrees and reduce the temperature to 350°F. Bake for 20 minutes more, or until the internal temperature reaches 204°F and the crust is golden and shiny.

Step 20

Transfer the baking pan to a wire rack and let cool for 10 minutes. Remove the rolls from the pan, place on a wire rack, and let cool for at least 30 minutes before eating. These rolls are best the day they’re made but are great the next day with a quick reheat in a warm oven.