Serves 8 to 10
4 to 5 pounds boneless, skinless pork shoulder, butterflied
3 tablespoons fine sea salt, divided
2 tablespoons very finely chopped garlic
2 teaspoons crushed fennel seed
1 teaspoon coarsely crushed black peppercorns
1 tablespoon fennel pollen, optional
3 tablespoons finely chopped fresh rosemary
3 tablespoons finely chopped fresh sage
¼ cup finely chopped wild fennel fronds and flowers, optional
Lightly score the skin and fat in a crosshatch pattern using a sharp knife. Flip over the meat and lay it open like a book, fat-side down on the work table with the flappiest side closest to you. Similarly score meat to open the spaces between layers between meat and fat. Season evenly with 2 tablespoons salt, rubbing salt in between layers of fat and meat so all inside surfaces are coated. Do the same with garlic, fennel seed, fennel pollen, bpc, rosemary, sage, and wild fennel (if using), giving attention to the in-between layers.
Starting with the side closest to you, roll the shoulder up like a jelly roll so that the skin and fat remain the outer surface of the roll. Secure with kitchen twine in 5 to 7 ties about 2 inches apart. Sprinkle the outside of the loin with the remaining tablespoon of salt; roll it on the table to collect any stray herbs. Refrigerate overnight.
Remove roast from refrigerator and bring to room temperature before roasting. Preheat oven to 425°F (220°C). Place fat-side up on a wire rack in a roasting pan. Roast for one hour, until the fat is crisp. Reduce heat down to 325º F (160°C) and cook until the internal temperature reaches 168° F (75°C), about 60 to 80 minutes longer; test in several spots to be sure of your measurement.
Allow to rest 30 minutes before slicing, or serve cold the next day.