Cook pork according to this Ultra-Crispy Slow-Cooked Pork Recipe.
While pork cooks, bring a large pot of salted water to a rolling boil. Add broccoli rabe and cook, stirring occasionally, until bright green but still crunchy, about 2 minutes. Remove broccoli rabe and run under cool water to chill. Spin in a salad spinner to dry. Set aside.
Heat olive oil in a large saucepan over medium heat until shimmering. Add garlic, anchovies, and red pepper flakes and cook, stirring, until fragrant, about 1 minute. Add broccoli rabe and stir to coat with oil. Continue cooking until broccoli rabe is fully tender, about 2 minutes. Transfer to a large bowl and set aside or refrigerate until ready to construct sandwiches.
When pork is cooked, remove skin (if present) and chop into fine pieces. Shred meat from bones and discard bones. Combine meat and skin in a large bowl, add vinegar, and season with salt, pepper, and red pepper flakes to taste, gently shredding meat with your fingers.
To serve: Preheat broiler to high. Place a dozen toasted bun bottoms on a rimmed baking sheet. Top with pulled pork, broccoli rabe, and a slice of cheese. Broil until cheese is melted, about 1 1/2 minutes. Top with pickled pepper slices and top buns and serve immediately. Repeat with remaining buns and fillings.
Note: Broccoli rabe and pork can be cooked in advance and stored in sealed, refrigerated containers for up to 3 days. Reheat pork in the microwave or in a pot on the stovetop before constructing sandwiches.
Recipe and Picture by J. Kenji Lopez-Alt
of Serious Eats www.seriouseats.com