Step 1

Preheat oven to 325°. Season pork with pepper and 2 tsp. salt. Heat oil in a medium Dutch oven or other heavy pot over medium high heat and cook pork until golden brown on all sides, 8–10 minutes. Stir in onion to coat, then add beer and bring to a simmer.

Step 2

Cover and cook in oven until pork is falling apart, 2 1/2–3 hours. Let cool slightly. Shred pork with 2 forks, mixing with braising liquid and onion; season with salt and pepper.

Step 3

DO AHEAD: Pork filling can be made 5 days ahead. Let cool; cover and chill.

Step 4

Preheat oven to 425°. Gently warm milk in a small saucepan over medium heat until warm (do not let it get hot). Transfer to the bowl of a stand mixer and whisk in yeast and brown sugar. Let sit until yeast starts to foam, about 5 minutes. Add flour, salt, baking powder, and butter and knead with dough hook until dough is smooth and elastic, about 5 minutes. (Dough should not be sticky or tacky.)

Step 5

Lightly coat a medium bowl with nonstick spray and transfer dough to bowl. Cover with plastic wrap and let stand in a warm, draft-free place until doubled in size, 1 1/2–2 hours. Alternatively, cover dough and chill overnight.

Step 6

Divide dough into 10 pieces. Using the palm of your hand, gently roll pieces on an unfloured surface into balls. Loosely cover with plastic wrap and let stand 10 minutes.

Step 7

Using the palm of your hand, flatten each ball into 3”-diameter rounds. Place 2 Tbsp. pork filling in the center of each round. Bring up edges and pinch together to create a parcel. Gently roll buns, seam side down, to close.

Step 8

Bring 2 quarts salted water to a boil and add baking soda.

Step 9

Line a rimmed baking sheet with parchment paper and spray with nonstick spray.

Step 10

Working in batches, boil buns 2 minutes (they will puff up and float, so don’t crowd the pot). Using a slotted spoon, transfer to prepared baking sheet, spacing about 1 1/2” apart.

Step 11

Brush buns with egg and sprinkle with sea salt. Bake, rotating halfway through, until golden brown, 20–25 minutes.

Step 12

Serve immediately with mustard, pickles, and beer.