Preheat barbecue to high heat. Slightly overlap three, 2-foot long sheets of aluminum foil. Brush the centre of the foil with the oil. Trim the tail and fins from the fish. Rinse the fish under cold water, pat dry, and place in the centre of the foil. Use a sharp knife and make several shallow cuts through the skin on the top of the fish. Stuff the fish with cilantro or mint and onion. Combine the curry paste and lime juice in a bowl. Brush all over the top and sides of the fish. Fold the foil over the fish; crimp at the top to seal. Place the foil package on one side of the barbecue and turn the heat off directly underneath it; leave the other side set to high. Close the lid and cook the fish 25 to 30 minutes, or until cooked through. Open the foil, carefully transfer the salmon to a platter, and serve.