Pat the pork belly dry with paper towels and score the skin in a crisscross pattern.
Rub salt, pepper, and garlic into the meat side, keeping the skin dry. Brush the skin with vinegar.
Let the pork belly dry in the fridge uncovered for at least 12 hours.
Preheat the oven to 300°F (150°C). Place the pork on a wire rack over a roasting pan and cook for 2 hours.
Increase the oven temperature to 450°F (230°C) and roast for an additional 30 minutes until the skin is crispy.
Remove from the oven, let it rest for 10 minutes, then slice and serve.