Pan-Roasted Mahi Mahi with Garlic and Vinegar

I had a version of this dish at a restaurant in the picturesque town of Grado, which juts into the Adriatic just west of Trieste in Friuli. Our host explained how fishermen prepared imperfect or damaged (but very fresh) fish that could not be sold. The acidity of the red wine vinegar is just barely noticeable, but its fragrance comes through, making this a fine dish. Bluefish and mackerel are excellent alternatives to mahi mahi.