Step 1

Using sharp chef’s knife, slice pork belly lengthwise into 3 strips about 2 inches wide, then make 1/4-inch-deep crosswise cuts through skin and into fat spaced 1/2 inch apart. Combine 2 tablespoons salt and brown sugar in small bowl. Rub salt mixture into bottom and sides of pork belly (do not rub into skin). Season skin of each strip evenly with 1/2 teaspoon salt. Place pork belly, skin side up, in 13 by 9-inch baking dish and refrigerate, uncovered, for at least 12 hours or up to 24 hours.

Step 2

Adjust oven rack to middle position and heat oven to 250 degrees. Transfer pork belly, skin side up, to lightly greased wire rack set in rimmed baking sheet. Roast pork belly until meat registers 195 degrees and paring knife inserted in meat meets little resistance, 3 to 3 1/2 hours, rotating sheet halfway through roasting.

Step 3

Transfer pork belly, skin side up, to large plate. (Pork belly can be held at room temperature for up to 1 hour.) Pour fat from sheet into 1-cup liquid measuring cup. Add vegetable oil as needed to equal 1 cup and transfer to 12-inch skillet. Arrange pork belly, skin side down, in skillet (strips can be sliced in half crosswise if skillet won’t fit strips whole) and place over medium heat until bubbles form around pork belly. Continue to fry, tilting skillet occasionally to even out hot spots, until skin puffs, crisps, and turns golden, 6 to 10 minutes. Transfer pork belly, skin side up, to carving board and let rest for 5 minutes. Flip pork belly on its side and slice 1/2 inch thick (being sure to slice through original score marks). Reinvert slices and serve.