Step 1 – Prepare the marinade: Combine soy sauce, calamansi or lemon juice, brown sugar, minced garlic, oyster sauce, banana ketchup, ground black pepper, and salt in a large bowl. Mix well until sugar dissolves.Step 2 – Marinate the pork belly: Add the pork belly slices to the marinade and massage it into the meat. Cover and refrigerate for at least 2 hours (overnight recommended for best flavor).Step 3 – Cooking Options:Grill Method:Preheat grill to medium-high.Brush grill with oil to prevent sticking.Grill pork belly slices 6–8 minutes per side, brushing with leftover marinade.Move closer to coals for 1–2 minutes for crisp edges.Rest meat 5 minutes before slicing.Air Fryer Method:Preheat air fryer to 190°C (375°F).Arrange pork in a single layer.Cook 15 minutes, flip, then cook 10–12 minutes more.Brush extra marinade in last 5 minutes.Oven-Baked Method:Preheat oven to 200°C (400°F).Line tray with foil and place pork on a rack.Bake 30 minutes, flip, bake another 25–30 minutes.Broil 3–5 minutes for crispy edges.Step 4 – Serve: Pair with garlic fried rice, steamed jasmine rice, atchara, ensaladang kamatis, grilled vegetables, or a simple vinegar dipping sauce.