Directions

1. 1

   In a large bowl, stir together kosher salt, 1/2 cup sugar, and 4 cups of water until the salt and sugar dissolve completely. Place the pork belly quarters into a large resealable bag and pour the brine mixture over the meat. Carefully press out excess air, seal the bag tightly, and place it in a shallow dish. Refrigerate for at least 12 hours, allowing the pork to absorb the flavors of the brine.

2. 2

   In a small bowl, combine 1/4 cup of the warm water with the active dry yeast and a pinch of sugar. Let this mixture stand for 5 to 10 minutes until it becomes foamy and bubbly. If the yeast does not foam, start over with fresh yeast. Once foamy, whisk in the dried milk and the remaining 3/4 cup of warm water.

3. 3

   In a large bowl, stir together the cake flour and 3 tablespoons of sugar. Pour the yeast mixture into the dry ingredients and stir with a fork until a shaggy dough begins to form. Do not add the baking powder at this stage. Using your hands, knead the dough in the bowl until all the flour is incorporated. Turn the dough onto a lightly floured surface and continue kneading for about 5 minutes, dusting with just enough flour to prevent sticking, until the dough becomes smooth, elastic, and soft.

4. 4

   Shape the dough into a ball and place it in an oiled large bowl, turning to coat all sides with oil. Cover the bowl tightly with plastic wrap and let the dough rise in a warm, draft-free place for about 2 hours, until it has doubled in size.

5. 5

   Preheat the oven to 300°F with the rack positioned in the middle.

6. 6

   Remove the pork belly from the brine and discard the brine. Place the pork pieces fat side up in an 8- to 9-inch square baking pan. Pour the chicken broth and remaining 1/2 cup of water around the pork. Cover the pan tightly with aluminum foil and roast for about 2 1/2 hours, until the pork is very tender and falls apart easily. Remove the foil, increase the oven temperature to 450°F, and roast uncovered for an additional 20 minutes until the fat is golden brown. Allow the pork to cool for 30 minutes at room temperature, then chill uncovered until completely cold, about 1 hour.

7. 7

   Once the pork is chilled, slice it across the grain into 1/4-inch-thick slices. Return the sliced pork to the pan with the cooking liquid, cover, and keep refrigerated until ready to assemble the buns.

8. 8

   Punch down the risen dough and transfer it to a lightly floured surface, flattening it gently into a disk shape. Sprinkle the baking powder over the center of the dough. Gather the edges of the dough up and pinch them together to seal in the baking powder. Knead the dough for about 5 minutes, using just enough flour to prevent sticking, until the baking powder is fully incorporated. Return the dough to the bowl, cover with plastic wrap, and let it rest for 30 minutes.

9. 9

   Cut 16 pieces of wax paper, each roughly 3 by 2 inches.

10. 10

    Shape the rested dough into a long log approximately 16 inches in length. Cut the log into 16 equal pieces and lightly dust each piece with flour. Cover loosely with plastic wrap. Take one dough piece and roll it on a lightly floured surface into a 6- by 3-inch oval. Gently pat the oval between your palms to remove excess flour, then brush half of the oval lightly with canola oil. Fold the oval in half crosswise without pinching the edges together. Place the folded bun on one piece of wax paper on a large baking sheet. Repeat this process with all remaining dough pieces, arranging them on the baking sheet. Cover loosely with plastic wrap and let stand for about 30 minutes until slightly puffed.

11. 11

    Set a large steamer rack inside a skillet or wok and fill with enough water to come within 1/2 inch of the bottom of the rack. Bring the water to a boil over high heat. Carefully place 5 to 7 buns (still on their wax paper) onto the steamer rack, ensuring they do not touch each other. Cover tightly and steam over high heat for about 3 minutes until the buns are puffed and cooked through. Using tongs, transfer the steamed buns to a plate, discard the wax paper, and wrap the buns in clean kitchen towels (not terry cloth) to keep them warm. Repeat steaming with the remaining buns in 2 more batches, adding boiling hot water to the skillet as needed between batches.

12. 12

    Keep the steamed buns wrapped in the kitchen towels and return them to the steamer rack in the skillet, covered but off the heat, to stay warm until serving.

13. 13

    Preheat the oven to 350°F with the rack in the middle. Place the baking pan with the sliced pork and its liquid into the oven, covered, for 15 to 20 minutes until the pork is heated through to serving temperature (the pork was already fully cooked during the initial roasting).

14. 14

    Brush the bottom half of each warm bun lightly with hoisin sauce. Layer 2 to 3 slices of warm pork onto the sauced bottom half. Top with cucumber slices and scallion strips, then gently press the top half of the bun down to close. Serve immediately.