Step 1

Two days before you plan to serve the porchetta, prepare the pork belly: Place the pork belly on a large cutting board. In a small bowl, mix together 1/2 cup salt and the sugar. Sprinkle the salt-sugar mixture all over the pork belly, then use your hands to rub it over every inch of the meat and skin; don’t forget the sides and corners! Wrap the pork belly tightly in a few layers of plastic wrap, then place, skin side down, on a large rimmed baking sheet. Transfer to the refrigerator and chill for 24 hours.

Step 2

Make the salsa verde: In a large bowl, combine the greens, Treviso and scallions. Pour in the olive oil and stir to combine. Cover with plastic wrap and refrigerate the salsa until ready to serve, up to 2 days. (Note that you’ll stir lemon juice into this salsa before serving with the porchetta.)

Step 3

Arrange a couple layers of paper towels that are larger than the pork belly on a work surface. Place the pork belly in your sink, unwrap, then rinse thoroughly under cold running water. Transfer the belly to the paper towels and pat the belly dry. Set aside on a clean work surface, skin side down.

Step 4

Make the herb and citrus paste: Pile the rosemary, thyme, sage and, if using, fennel fronds on a cutting board and run your knife over them back and forth, over and over, until very finely chopped. Transfer the herbs to a bowl and stir in 2 teaspoons kosher salt, the fennel pollen (if using), black pepper and Piment d’Espelette or chile flakes. Using a microplane, grate the garlic into the herb mixture, followed by all the zest of the lemons and oranges (this will take a while, I’m sorry); reserve all the zested fruit (you will use it to finish the porchetta and salsa verde). Finally, add the olive oil and stir everything together into a paste. Spread the herb-and-citrus paste evenly over the meat side of the pork belly.

Step 5

Arrange the trimmed pork loin parallel to and on top of one short side of the pork belly, and roll up the belly around the loin. If the belly doesn’t completely enwrap the loin, that’s OK. Position the roll seam side down on the work surface, set off to the side.

Step 6

On the work surface, arrange eight 36-inch-long pieces of kitchen twine parallel to each other, spaced about ½ inch apart. Place the pork roll, seam side down, across the center of the twine pieces. Starting with the middle twine piece, tie the twine as tightly as you can around the pork roll using 2 double knots (like tying ribbon on a gift box, it helps to have a friend hold one knot down with their finger while you tie the second to secure it). Working your way from the center toward either end, alternating direction as you go, continue tying the twine around the pork roll. Trim any excess twine with scissors and discard. Wrap the pork roll tightly in plastic wrap and return to the refrigerator to chill until ready to use or up to 24 hours more.

Step 7

When ready to cook the porchetta, remove it from the refrigerator 1 hour before you plan to place it in the oven. Unwrap the porchetta on a work surface, then sprinkle with the remaining 2 tablespoons kosher salt. Rub the salt all over the roll with your hands; don’t forget the ends! Place the roll on a wire rack and place the rack in a foil-lined, large rimmed baking sheet.

Step 8

Heat the oven to 275 degrees (yes, TWO-seventy-five); this low heat will help to properly render the pork belly skin so it becomes crispy in the end, not leathery and tough. Bake until an instant-read thermometer inserted in the middle of the roll through to the center of the loin reads 145 degrees, about 4 hours. Transfer the pork roll on the wire rack to a cutting board. Pour any pan drippings in the baking sheet into a bowl, then pour off the fat; save the fat for another use or discard. Keep the remaining pan drippings in a bowl; you should have 3 to 4 tablespoons.

Step 9

Increase the oven temperature to 450 degrees. Cut open all three of the reserved lemons and drag their cut sides through the fat on the baking sheet. Place the pork roll on the wire rack back on the baking sheet, then arrange the lemon halves on the rack around the porchetta, cut side up. Cut open both of the reserved oranges and squeeze their juices all over the pork roll, discarding any seeds and their spent hulls. Return the roll to the oven and bake until the skin is bubbly, crisp and lightly blackened at the edges and a thermometer inserted in the center of the roll reads 160 degrees, 25 to 30 minutes.

Step 10

Transfer the porchetta to a cutting board and tent loosely with a sheet of foil. Let stand for at least 30 minutes or up to 1 hour. Meanwhile, take the roasted lemon halves and squeeze their innards into the bowl of reserved pan drippings, discarding any seeds. Stir these lemony drippings into the salsa verde, season with salt and pepper and let stand at room temperature until ready to use.

Step 11

To serve, use kitchen shears to cut the twine off and discard. Use a long serrated or slicing knife to cut the porchetta crosswise into ½-inch-thick slices. Arrange the slices on a large, warm serving platter or cutting board, and if any crackling skin pieces fall off, break them into bite-size pieces and scatter them over the meat. Serve the porchetta with the roasted lemon salsa verde on the side.