Instructions

1. Heat a small skillet over medium-high heat. Add 1 tablespoon plus 1 1/2 teaspoons fennel seeds and 1 teaspoon whole black peppercorns. Toast, stirring frequently, until the fennel seeds start to turn light golden brown and are fragrant, 30 seconds to 1 1/2 minutes. Transfer to a spice grinder and let cool for 10 minutes.
2. Meanwhile, prepare the following, adding each to the same small bowl as it is completed: Pick the leaves from 10 fresh rosemary sprigs and finely chop until you have 2 tablespoons. Pick the leaves from 5 fresh sage sprigs and finely chop until you have 1 tablespoon plus 1 1/2 teaspoons.
3. Pulse the spices until coarsely ground and transfer to the bowl with the herbs. Add 1 tablespoon plus 1 1/2 teaspoons garlic powder and 1 tablespoon of the kosher salt, and stir to combine.
4. Pick the leaves from 1/2 medium bunch fresh parsley and finely chop until you have 1/2 cup. Transfer to a second small bowl. Finely grate the zest of 1 medium lemon into the bowl (about 1 tablespoon); reserve the zested lemon for serving. Mix together with your fingers, breaking up any clumps of lemon zest.
5. Butterfly the pork shoulder: Place a 3-pound boneless pork shoulder roast on a cutting board and pat dry with paper towels. Position it with a shorter side closer to you. Keeping your knife parallel to the cutting board, cut into the pork on one side about 1-inch up from the cutting board, cutting horizontally and then stopping about 1-inch from the other side.
6. Open the roast up like a book. Starting where the “fold” of the book is, repeat cutting horizontally in the same direction, stopping again when you are about 1-inch from the other side. Repeat this process until the pork is fully butterflied into one piece that’s about 1-inch thick. (Here’s a helpful video.)
7. Sprinkle the cut side of the pork evenly with 2/3 of the spice mixture (about 1/4 cup), pressing it into the meat. Sprinkle all of the lemon-parsley mixture evenly on top. Roll the pork back up so it forms a roast again. (If the piece is too long to sit flat in the pressure cooker, cut it into 2 pieces.) Tie the roast together with kitchen twine. Season all over with the remaining spice mixture. Place in a large zip top bag. Seal the bag and refrigerate for at least 8 or preferably 24 hours.
8. Peel, halve, and thinly slice 1 large white or yellow onion.
9. Heat 2 tablespoons olive oil in an Instant Pot or electric pressure cooker on the highest Sauté function until shimmering. Add the pork and sear until browned on all sides, 3 to 4 minutes per side. Transfer to a plate.
10. Add the onions, 1 cup low-sodium chicken broth, and 1/2 cup dry white wine to the pot and stir to combine, scraping up the browned bits at the bottom with a wooden spoon. Bring to a simmer. Return the pork and any accumulated juices on the plate to the pot. Turn off the pressure cooker.
11. Lock the lid on and make sure the valve is set to seal. Set to cook on HIGH pressure for 75 minutes. It will take about 9 minutes to come up to pressure. Meanwhile, pickle the peppers.
12. Place 1/4 cup red wine vinegar, 1 1/2 teaspoons granulated sugar, and the remaining 3/4 teaspoon kosher salt in a medium bowl and whisk until the salt and sugar are dissolved. Trim and thinly slice 6 Fresno peppers into rings. Add to the bowl and stir to combine. Let sit while the pork is cooking, stirring once or twice.
13. When the cook time is complete, let the pressure release naturally for 20 minutes. Transfer the pork to a rimmed baking sheet and let cool for 15 minutes. Meanwhile, pour the cooking liquid and onions into a 4-cup glass measuring cup or medium heatproof bowl. Spoon off the fat from the surface into a small bowl.
14. Cut off and discard the kitchen twine. Using 2 forks, pull the meat apart into big, shreddy pieces. Heat 3 tablespoons of the fat in a large skillet over medium-high heat until shimmering. Add the pork and arrange into an even layer. Cook undisturbed until the bottom is crisp and well browned, 3 to 5 minutes. Add 3/4 cup of the reserved cooking liquid and onions and stir to combine. Cook until the liquid is reduced by about half and coats the meat, about 2 minutes. Remove the pan from the heat. Taste and season with more kosher salt as needed.
15. To assemble the sandwiches, split 8 ciabatta rolls in half horizontally with a serrated knife. Halve the reserved lemon. For each sandwich, pile a generous amount of the pork on the bottom half of the roll (about 3/4 cup), top with the desired amount of the pickled peppers, and top with a handful of baby arugula. Squeeze a spritz of lemon juice over the arugula and close with the top half of the roll. Cut in half if desired.