24 hours before you want to cook your pork belly, remove all the packaging and place it in a large casserole dish or oven proof dish. Rub the five spice and salt all over it, cover and put in the fridge.
When you’re ready to cook, preheat the oven to 140 degrees Celsius.
Remove the casserole dish from the fridge and pour in the soy sauce, teriyaki sauce, rice wine and sugar. Use tongs to turn the pork a few times, ensuring that the meat is coated in the sauce. Put back in the dish fat side up.
Put a tight lid or kitchen foil over the casserole dish and put in the oven for three hours. Remove from the oven every half an hour to turn the pork belly.
After three hours, remove from the oven and leave to cool in the dish. When you’re ready to eat, transfer to a plate or board and cut into thick slices.