Mackerel is a delicious fish packed with omega-3 fatty acids. The easiest way to cook it is to leave it whole and grill or bake it in the oven. Mackerel has a firm texture (think canned tuna) and can be used in the kitchen almost any way! Use it as the protein in a salad, grill it with a side of vegetables and rice, or toss it in a sandwich with a lemon aioli.