2 tablespoons (30 milliliters) ground black pepper, divided
4 tablespoons (60 milliliters) salt, divided
4 tablespoons (60 milliliters) extra virgin olive oil, divided
1/4 cup (60 milliliters) fennel seeds
3 tablespoons (45 milliliters) dried sage
2 rosemary sprigs, leaves only
6 cloves garlic, roughly chopped
Lay pork belly out on working surface, skin side down. Slice flesh in cross-hatch pattern, about 2.5 centimeters apart and seven millimeters deep. Rub the ground black pepper and remaining two tablespoons (30 milliliters) of salt into flesh. Set pork belly aside.
Toast fennel in a large skillet over medium heat. Transfer to a food processor or mortar and pestle. Add dried sage, rosemary needles, chopped garlic, and extra virgin olive oil to blend or grind to a rough paste. Set aside.
With the pork belly laid out in front of you, skin-side down, spread 1/2 the spice mixture evenly over the flesh, leaving a 1.25 centimeter border. Butterfly the pork loin and lay out like an open book on top of the pork belly. Spread the remaining spice mixture, leaving a 1.25 centimeter border. Carefully roll the pork belly with pork loin and tie roast with butcher’s twine. Trim ends of pork belly if required. Place roast on wire-rack topped baking sheet in refrigerator, uncovered, overnight.
Allow porchetta to sit out at room temperature for one to two hours before roasting. Rub porchetta with remaining salt.
With rack in middle position, preheat oven to 325 F (160 C).
Roast for three to three and a half hours or until thermometer inserted in the centre reads 140 F (60 C). Increase heat to 450 F (230 C) for the last 20 minutes to crisp up the skin.
Remove porchetta from oven and let sit at room temperature for 30 minutes before serving.