• Toast fennel seeds and peppercorns in a pan on the stovetop or in the oven until lightly browned and fragrant (approximately 2-3 minutes). Cool. Grind to a fine powder in a spice grinder or with a mortar and pestle. Set aside.
• Mix together lemon zest, rosemary, sage, garlic and thyme. Add ground fennel seed and peppercorn mixture.
• Place the pork belly skin-side down on a large cutting board. With a sharp knife, score the flesh (taking care not to cut all the way through) in a cross-hatch pattern (like Tic-Tac-Toe), with cuts approximately one inch apart.
• Sprinkle pork belly with one (1) tablespoon of the kosher salt. Rub the lemon zest/herb mixture across the surface, pressing into the scored cuts.
• Roll the pork belly lengthwise, as tightly as possible. Roast will be 12-18 inches long. Tie at 2-3 inch intervals with kitchen twine.
• Rub skin with remaining one (1) tablespoon of kosher salt and baking powder.
• At this point, cut the roast into two. Wrap one half tightly in cling wrap and foil; freeze for use at a future date. Wrap the other half tightly in cling wrap and store it in the refrigerator for 12-36 hours.

Cooking the porchetta

• Remove the porchetta roast from the refrigerator about an hour before cooking.
• Preheat oven to 300 degrees Fahrenheit.
• Place a v-shaped roast rack or wire rack in a large roasting pan to keep roast from coming into contact with liquids/drippings.
• If making the cider sauce, core and slice the apples, leaving the skins on. Cut onion and celery or fennel bulb into 3-4 inch pieces. Place apples and celery/fennel in bottom of roasting pan.
• Add cider (if using) to pan to a depth of about an inch, making sure it does not come in contact with the roast.
• Baste roast every 30 minutes with pan drippings, replenishing cider if needed. Roast until internal temperature of the roast reaches 160 degrees Fahrenheit (approximately 3-3.5 hours). Meat should feel tender when pierced with a knife.
• Increase oven temperature to 500 degrees Fahrenheit (or turn on broiler) to crisp skin, approximately 15-20 minutes. If skin on bottom of roast is not browned, roll roast over and brown under broiler.
• Remove roast from oven to a plate or cutting board and let it rest under foil for about 15 minutes before serving.

Making cider sauce

• Strain the liquid from the bottom of the roasting pan into a bowl. Discard solids.
• Skim off fat.
• Heat remaining liquids in a saucepan over medium heat; bring to a boil.
• Dissolve flour in water and stir into cider sauce. Simmer for 5-10 minutes. Season to taste with salt and pepper.
• Serve alongside roast.