For skinless pork belly, move on to the next step. If using skin on pork belly, pat skin dry with a paper towel. With a sharp knife, score through skin every ½-inch at a diagonal, cutting through skin and into fat, but not so deep that you hit meat. Repeat cutting in an opposite diagonal to create a diamond shape pattern. (recipe note #1)
Season pork belly with salt sugar and a few grinds of black pepper. Cover and refrigerate overnight.
Preheat oven to 450°F.
Roast pork belly for 30 minutes on the middle rack in a heavy, oven-safe pan or skillet, skin side up / fat side up. Reduce heat to 275°F and roast for an hour or more, until tender but not mushy. (Larger pieces of pork belly will take longer. Our one-pound belly was done after an hour at 275°F.)
Remove from oven and let cool to room temperature. Wrap tightly in plastic and refrigerate until chilled through - at least a few hours and up to 2 days.
Once chilled, slice into thick pieces and brown in a skillet on the stovetop until crisp. Enjoy alone or in soups, salads, pasta sauces, ramen and more! (recipe note #2)