Park 121 makes its own zucchini pickles for these messy (in a good way) sandwiches; substitute with thinly sliced dill or bread-and-butter pickles if you like.

Ingredients
SERVINGS: 8
Zucchini Pickles
1 ½ cups apple cider vinegar
½ cup sugar
1 teaspoon ground turmeric
1 teaspoon mustard powder
1 teaspoon mustard seeds
1 large zucchini, sliced into ⅛”-thick rounds, preferably on a mandoline
½ large onion, thinly sliced
2 tablespoons kosher salt
Shredded Pork And Assembly
1 medium onion, chopped
1 medium carrot, peeled, chopped
1 celery stalk, chopped
1 sprig oregano
1 sprig rosemary
1 teaspoon crushed red pepper flakes
2 cups low-sodium chicken broth
1 3-lb. skinless, boneless pork shoulder (Boston butt)
2 tablespoons olive oil
Kosher salt, freshly ground pepper
½ cup mayonnaise
2 tablespoons Dijon mustard
8 brioche buns, split
8 ounces soppressata, thinly sliced
8 ounces pepper Jack, thinly sliced

Preparation

Zucchini Pickles
Bring vinegar, sugar, turmeric, mustard powder, and mustard seeds to a boil in a medium saucepan, stirring to dissolve sugar. Let cool.

Toss zucchini, onion, and salt in a large bowl and let stand until zucchini releases moisture, 30–35 minutes. Pat zucchini and onion dry and transfer to a large jar. Pour pickling liquid over vegetables to submerge. Cover and chill at least 12 hours.

Do Ahead: Zucchini can be pickled 
4 days ahead. Keep chilled.

Shredded Pork And Assembly

Preheat oven to 300°. Combine onion, carrot, celery, oregano, rosemary, red pepper flakes, and broth in a Dutch oven or other large pot. Place pork on top of vegetables and drizzle with oil; season pork with salt and pepper. Cover and braise, turning pork occasionally, until pork is just falling apart, 3½–4 hours. Let cool.

Transfer pork to a large bowl, reserving 1 cup cooking liquid, and shred with a fork. Add cooking liquid as needed to moisten pork (you may not use all of it).

Meanwhile, increase oven temperature to 400°. Mix mayonnaise and mustard in a small bowl and set aside.

Place both halves of buns, cut side up, on a rimmed baking sheet. Layer soppressata, pork, and cheese on bottom halves of buns and bake until cheese is melted, about 
5 minutes. Top bottom halves of buns with pickles; spread top halves of buns with reserved mayonnaise mixture and form sandwiches.

Do Ahead: Pork can be braised and shredded 3 days ahead. Cover and chill. Bring to room temperature before using.