Arrange fish fillets or steaks in a shallow glass or earthenware bowl. Combine remaining ingredients and pour over fish. Marinate in this mixture for at least 2 hours.
When ready to cook: place fish on a well-oiled grill over glowing charcoal (or in a flat ovenproof dish under grill of your cooker). Cook for 10 to 15 minutes, brushing from time to time with marinade juices. Turn and con