In a small bowl, combine the hoisin, sugar, soy sauce, Chinese 5 spice, honey and optional chili peppers.
Place the pork belly into a deep roasting pan (sides of the pan should be at least as high as the piece of pork) and pour the marinade over the top; cover well with plastic wrap. Let the pork soak in the marinade overnight, or up to 4 days under refrigeration.
Heat the oven to 350˚F. Remove the pork from the fridge. Cover the marinated pork belly with water until submerged, and cover with foil, then put the roasting pan into the hot oven and bake for 3 hours.
Remove the pork belly from the oven and let it cool for 1 hour. To press the pork belly, place it on a new baking sheet or into a shallow pan with a sheet of parchment paper over the pork and put something heavy on top of the parchment (like a cast iron skillet or six-pack of beer). Place it into the refrigerator and let it “press” overnight.
To serve, cut the pork belly into slices and warm in the oven at 350˚F for 5 mins or frying pan on medium heat with a teaspoon of oil in the pan. Enjoy with hot rice or your favorite noodle dish and pair with a white or red wine.