Prep the pork belly - Pat the pork belly with paper towels, drying it thoroughly, especially the skin - you want it to become crispy, crunchy. Refrigerate the pork belly, uncovered, for at least 3 hours or preferably overnight. This removes any excess moisture.
Preheat the oven; prep the pork belly for roasting - Preheat the oven to 250℉. Using a very sharp knife, score the skin in a diamond pattern, cutting through the skin and fat but not into the meat itself. Rub salt into the scored skin, in and around all of the cuts.
Roast - Place the pork, skin-side up, on a wire rack set in a rimmed baking sheet lined with parchment for easy clean-up. Roast until the meat is tender, about 2 hours.
Crisp the pork belly skin - Increase the oven temperature to 400℉ for the final 20–40 minutes of roasting. Watch it closely during this stage as the skin quickly transforms into a golden-brown, bubbly crackling. You want to remove it from the oven as soon as it reaches this stage, before it chars.
Rest, slice, and serve - Allow the pork belly to rest for at least 10 minutes so that the juices redistribute throughout the meat. Slice and serve.