Directions

1. 1

   Using a sharp knife, lightly score the fat cap of each roast in a 1-inch crosshatch pattern, being careful not to cut into the meat underneath.

2. 2

   Toast the black peppercorns and fennel seeds in a small dry skillet over medium heat, shaking the pan occasionally, until fragrant and just beginning to smoke, about 4 minutes. Transfer to a spice mill or mortar and pestle, let cool slightly, then add the red pepper flakes and ground cinnamon. Finely grind everything together.

3. 3

   Using a skewer or paring knife, poke several holes deep into the meat all over both roasts to help the seasoning penetrate. Generously rub the roasts with the kosher salt, then apply the ground spice mixture evenly over all surfaces. Wrap each roast tightly in plastic wrap and refrigerate for at least 8 hours (or up to 2 days ahead).

4. 4

   Remove the roasts from the refrigerator and unwrap them. Allow them to come to room temperature for about 1 hour before cooking.

5. 5

   Position a rack in the lower third of your oven and preheat to 275°F. In a small saucepan over medium-low heat, combine the butter, one garlic half, and 1 thyme sprig. Cook, stirring often, until the mixture is bubbling and fragrant but not browned, about 5 to 6 minutes. Remove from heat and cover the pan to keep the butter warm.

6. 6

   In a large roasting pan, toss together the leek rounds, potatoes, olive oil, the remaining garlic halves, and the 5 remaining thyme sprigs. Season with kosher salt. Place the pork roasts on top of the vegetable mixture. Brush the pork all over with some of the garlic butter. Roast the pan, basting the pork with the garlic butter every 30 minutes and stirring the vegetables occasionally. Continue roasting until an instant-read thermometer inserted into the center of the pork registers 145°F, which should take 75 to 105 minutes. Transfer the pork to a cutting board and tent loosely with foil. Allow the meat to rest for at least 45 minutes or up to 3 hours.

7. 7

   Check the potatoes for doneness by piercing them with a fork—they should offer no resistance. If they are still firm, increase the oven temperature to 500°F, cover the roasting pan with foil, and continue roasting until the potatoes are tender and the garlic is golden, about 20 to 30 minutes longer (start checking after 10 minutes).

8. 8

   If you have rested the pork for the full 3 hours, turn off the oven and remove the foil from the pan. Once the pork has finished resting, preheat the oven to 500°F again. Add the torn kale and apple cider vinegar to the roasting pan and toss everything to coat well. Arrange the rested pork roasts on top of the vegetables and roast until the pork is deeply golden brown and an instant-read thermometer inserted into the center registers 145°F, about 10 to 20 minutes (or possibly longer if the pork was rested the full 3 hours). Let everything rest in the pan for 15 to 20 minutes.

9. 9

   Transfer the pork to a cutting board. Using tongs, transfer all the vegetables to a large serving platter, reserving any pan juices. Carve the meat away from the bones, then slice the meat crosswise into ½-inch-thick slices. Arrange the sliced pork over the vegetables on the platter. Spoon the reserved pan juices over the meat and vegetables. Season everything to taste with flaky sea salt before serving.