For the porchetta: To prepare the pork, debone the pork middle. Remove the spareribs and tenderloin. Cut any extensive belly fat out and make a pocket in the pork belly for stuffing. Use a sharp knife to cut back the fat of the loin, avoiding cutting into the loin.
Combine the fennel seeds, garlic, lemon zest, rosemary, sage, salt, wine and pepper in a small bowl until well incorporated. Rub the spice blend into the pork evenly, including the pork belly pocket.
Roll up the loin inside the belly, then tie the roast at 2-inch intervals with heavy butcher twine. Make sure you use the same force while tying the porchetta so it can cook evenly. Wrap the porchetta in plastic wrap and refrigerate for 24 hours.
For the onion marmalade: Set a heavy saucepan over low heat and add the oil, onions and a few teaspoons of water. Cook the onions, stirring occasionally, until the water evaporates and the onions start to caramelize, about 1 hour. Season the onions with the salt. Add the balsamic vinegar gradually, cooking until the onions taste sweet, another 3 hours.
Cook the porchetta on a rotisserie at a low temperature until the meat reaches an internal temperature of 145 degrees F on a probe.
Alternatively, cook the porchetta in the oven: Preheat the oven to 450 degrees F.
Put the roast seam-side up on a rack in a roasting pan. Roast for 30 minutes, then lower the temperature to 350 degrees F and continue to cook until the internal temperature of the meat registers 145 degrees F, another 1 hour 15 minutes. For the last 5 minutes, turn the oven to broil and crisp up the porchetta skin until golden brown.
Let the porchetta rest for 15 minutes. Remove the twine and slice into 1/4-inch slices.
For the sandwiches: Cut each roll in half and top with 6 to 7 ounces porchetta per sandwich. Add 2 tablespoons of the onion marmalade and 1/2 cup arugula per sandwich. Sprinkle each with 1/4 teaspoon sea salt or to taste.
Pork middle can be found at specialty butchers. If not available, substitute a combination of pork loin and pork belly.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.
Recipe courtesy of Thomas Odermatt, RoliRoti, San Francisco, California