Prepare the Pork Belly: Start by rinsing the pork belly and patting it dry with paper towels. Use a sharp knife to score the skin deeply, ensuring you cut through the skin and into the fat layer.
Marinate the Pork: In a bowl, mix the salt, five-spice powder, white pepper, sugar, Shaoxing wine, vinegar, minced garlic, light soy sauce, dark soy sauce, and red fermented tofu (if using). Rub this mixture thoroughly over the pork, ensuring it reaches the cuts in the skin.
Refrigerate: Place the marinated pork in the refrigerator uncovered for at least 12 hours or overnight. This allows the skin to dry, resulting in crispy crackling.
Preheat the Oven: Preheat your oven to 220°C (430°F).
Roasting: Place the marinated pork on a wire rack in a roasting pan, with a shallow layer of water in the pan. Roast for 30 minutes at 220°C to crisp the skin. Then, reduce the heat to 160°C (320°F) and roast for an additional 1.5 hours, or until the pork reaches an internal temperature of 70°C (160°F).
Rest and Slice: Once done, let the roast pork rest for 10 minutes before slicing it into mouthwatering pieces.