Mackerel, two ways: In this recipe half the mackerel is coated with flour, fried to a crisp, and served with a seasoned tomato sauce. The other half is poached and then served with potatoes and a salad. You could make just one or the other, of course, but each one somehow tastes better when served with the other, as a sort of tapas for sharing with others. To make the tomato sauce, be sure to cook the onions until they are very tender with the wine and tomato paste.