2 packets active dry yeast
1/3 cup barely warm water
1/3 cup barely warm milk
3 1/4 cups all-purpose flour
2 tsp. salt
3 large eggs, at room temperature
1/4 cup sugar
3 sticks unsalted butter, at room temperature but still slightly firm
Put the yeast, water and milk in the bowl of a stand mixer and, using a wooden spoon, stir until the yeast is dissolved. Add the flour and salt, and fit the mixture with the dough hook, if you have one. Toss a towel over the mixer to avoid being showered in flour. Turn the mixer on and off in a few short pulses, just to dampen the flour, then remove the towel, increase the mixer speed to medium-high just until the flour is moistened. You should have a fairly dry, shaggy mass.
Create a marinade by transferring the paste to a small bowl and whisking in the soy sauce, fish sauce, five-spice powder and a healthy dose of pepper.Scrape the sides and bottom of the bowl with a rubber spatula, set the mixer to low and add the eggs, followed by the sugar. Increase the mixer speed to medium and beat for about 3 minutes, until the dough forms a ball. Reduce the speed to low and add the butter in 2-tablespoon size chunks, beating until each piece is almost incorporated before adding the next. You’ll have a dough that is very soft, almost like a batter. Increase the speed to medium-high and continue to beat until the dough pulls away from the sides of the bowl, about 10 minutes.
Transfer the dough to a clean bowl, cover with plastic wrap and leave at room temperature until nearly doubled in size, 40 to 60 minutes.
Deflate the dough by lifting it up around the edges and letting it fall with a slap into the bowl. Cover the bowl with plastic wrap and put it in the refrigerator. Slap the dough down in the bowl every 30 minutes until it stops rising, about 2 hours, then leave the covered dough in the refrigerator to chill overnight.
At this point, you’ll have two loaves worth of dough. Split the dough in two. Set aside one piece for the buns and either freeze the other for another time or bake it in a loaf pan. Butter and flour the loaf pan. Cut the dough into 4 equal pieces and roll each piece into a log about 3 1/2 inches long. Arrange the logs crosswise in the bottom of the pan. Cover the pan lightly with wax paper and leave the loaf at room temperature until the dough almost fills the pans, 1 to 2 hours. Brush tops with a mixture of egg and 1 tbsp. water. Bake in a 400 degree oven for 30 to 35 minutes.