For 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.
For Skinless Pork Belly: Move on to the next step.
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.
To Serve as Crispy Slices (Momofuku-Style): 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.
To Serve as a Roast (Skin-On Alternative): Remove from oven and let rest 10-15 minutes before slicing.
