Using a pestle and mortar, pound the garlic with 1 level teaspoon of salt until a smooth paste is formed, then add the cumin followed by the lemon juice, vinegar, paprika, coriander, olive oil and pepper.
Place the mackerel on a baking tray and slash them half a dozen times on each side. Rub two-thirds of the charmoula mixture all over the fish. The remaining third can be kept in the fridge for up to a week. Cover the fish with cling film and allow it to marinate in the fridge for between 20 minutes and 2 hours.
The mackerel can be roasted, pan fried or grilled. To roast the mackerel