Place all the ingredients for the curry paste in a small food processor and blend to a smooth paste.
Make 3 cuts in the skin of the fish on both sides. Place the fish in a non-metallic dish and pour over the marinade, making sure it gets into the cavity of the fish as well. Leave to marinate in the refrigerator for a minimum of 1 hour, but ideally 3–4 hours.
Place the fish on a medium-hot barbecue and cook for 4 minutes on each side, or until the flesh is firm.
Mix all the salsa ingredients and serve with the warm fish straight from the barbecue.