Combine pork belly, 1 red chilli pepper, lemongrass, 3 tablespoons fish sauce, 3 cloves garlic, 1 teaspoon sugar and five-spice powder in a bowl. Cover with cling film and refrigerate for 1 to 3 hours.
Mix 4 tablespoons fish sauce, 3 tablespoons sugar, 1 red chilli pepper, lime juice, 5 cloves garlic together in a bowl. Let sit until dipping sauce flavours meld, 30 minutes to 1 hour. Pour in water.
Thread the marinated pork onto bamboo skewers.
Preheat a charcoal barbecue for high heat and lightly oil the grilling grate. Cook pork kebabs, turning occasionally, until cooked through and slightly charred, 8 to 10 minutes. Serve with the dipping sauce.