Mash the garlic and mix it with the other spices, lemon juice and olive oil. Leave to mix all the flavors for at least 5 minutes. They'll turn into a paste - use it to coat the well cleaned and chilled mackerel.
Leave them as is for about 15 minutes. Wrap them in foil and grill while constantly turning them over. A very suitable garnish for the strong garlic flavor is boiled potatoes with dill.
You can cook trout the same way, which becomes even more tender. The recipe is for 2 servings. For more portions, increase the products accordingly.