Mix together everything for the marinade and pour over the mackerel. Cover and marinate for at least 1 hour.
Heat a grill to high and cover a baking sheet with foil. Place the marinated mackerel skin side up on the foil. Cook for 5 minutes, then turn, spoon over any remaining marinade, season with a little salt and pepper and cook for another 4 – 5 minutes until cooked through.
Serve with hot white rice and stir fried tenderstem broccoli if you like.