Heat the oil in a pan over a medium heat, then add the onion and cook for 5 minutes. Add the peppers and cook for 5-8 minutes until softened. Add the chilli, ginger, garlic, thyme and allspice and cook for 2 minutes. Add the coconut cream with a splash of water to loosen it slightly and simmer for 2 minutes. Remove from the heat and add the lime juice and sugar, then season to taste.
Make four packages by laying out a large sheet of tin foil with a sheet of greaseproof paper on top of it (you might need to trim this to make it roughly the same size as the foil). Place a salmon fillet on each, then slightly bring up the sides and divide the coconut sauce between each parcel. Scrunch the sides together to create a parcel, but leave enough space for the fish to steam.
Place each parcel on a hot barbecue or griddle pan for 8-10 minutes until the fish is just cooked through. Open the parcels and serve.