To make the roasted chilli sauce, heat the sugar and rice vinegar in a small saucepan. After it boils, let it reduce for 5 minutes and then remove from the heat. Add the chilli flakes, lime juice and fish sauce. Let cool and pour into a serving bowl.
To make the mango salsa, mix all the ingredients in a small bowl and set aside.
If using banana leaves, turn on your stovetop hob and run each banana leaf through the heat. This will soften them and make them pliable for wrapping. For the foil, use two for each parcel.
Place the fish on top of the banana leaf or foil squares. Mix the curry paste, fish sauce and coconut cream together. Spread over all sides of the fish. Sprinkle with the toasted coconut.
If using foil, bring the top and bottom together and fold twice for a secure package. Bring the sides in and fold the edges twice too. Make sure there is a little room so that the fish can steam. If using banana leaf, then fold the bottom over the fish and bring the top down. Bring the sides all the way over and secure with a toothpick. The fish can be wrapped and then refrigerated for up to 8 hours before grilling.
Preheat an outdoor grill. Grill over medium direct heat for about 12 minutes and then remove.
Serve the fish with lime wedges and scattered with coriander, along with the roasted chilli sauce for dipping and the mango salsa. Add rice and steamed greens for a more substantial meal.