Preparation

Braise the pork belly

• Position a rack in the center of the oven and heat the oven to 350°F. Pat the pork belly dry with paper towels. With a paring knife, cut a 3/4-inch crosshatch pattern through the fat, but not through to the meat. Season with 2 tsp. salt and 1 tsp. pepper.
• Heat the oil in a heavy-duty 7- to 8-quart pot over medium heat. Put the belly, fat side down, in the pot (cut to fit, if necessary) and cook until golden brown, about 7 minutes. Flip the belly, then add the carrots, celery, onion, fennel, hard cider, and broth. Cover, transfer to the oven, and braise until the pork is fork-tender, 2 to 3 hours. Remove from the oven and cool. Cut into 12 pieces, about 1 inch wide and 3 inches long. Discard the braising mixture.

Make the glaze

• Put the apple cider and hard cider in a 2-quart saucepan. Bring to a boil over medium heat, then reduce the heat to low and cook, stirring occasionally, until syrupy, about 1 hour.

使球芽甘蓝and serve

• Heat 2 Tbs. of the oil in a 12-inch skillet over medium-high heat. Add the pork belly and cook, fat side down, until the meat is warm and the fat softens, about 2 minutes. Transfer to a plate.
• Add the Brussels sprouts and cook undisturbed until browned on one side, about 3 minutes. Add 1/4 cup water, stir, and cook until tender, about 3 minutes more. Add the shallot and cook, stirring, until fragrant, about 1 minute. Add the vinegar and toss. Add the frisée, apple, nuts, and the remaining 3 Tbs. oil, and toss. Season to taste with salt and pepper.
• Brush the pork belly with the glaze, then drizzle the remaining glaze evenly over the Brussels sprout mixture. Top the Brussels sprout mixture with the pork belly pieces. Sprinkle with the Gorgonzola, and serve.

Make Ahead Tips

The belly pork belly can be braised up to two days ahead and refrigerated in an airtight container. Bring to room temperature before searing and glazing.