How to Make It
Preheat the oven to 300°. In a small bowl, combine the garlic with the rosemary, thyme, oregano, fennel seeds, crushed red pepper and salt; stir in the olive oil. Rub the mixture all over the pork. Set the pork in a large, enameled cast-iron casserole and cover with a tight-fitting lid. Roast in the oven for about 2 1/2 hours, turning once, until an instant-read thermometer inserted in the thickest part of the meat registers 180°. Let cool, then wrap the pork in plastic wrap and refrigerate overnight.
Preheat the oven to 450°. In a large pot, heat the olive oil. Add the garlic and crushed red pepper and cook over high heat until golden, 1 minute. Add the spinach in large handfuls and cook, stirring, until wilted, 3 minutes. Season the spinach with salt and transfer to a colander. Let cool slightly, then squeeze out the excess water.
Slice the cold pork very thinly, then let come to room temperature. Arrange the rolls on 2 baking sheets and mound the spinach on the bottom halves; layer the provolone on the top halves. Bake for about 5 minutes, until the cheese is melted. Pile the sliced pork on the rolls and top with the pickled peppers. Close the sandwiches and serve right away.