Sicilian cuisine is influenced by the food and cooking of North Africa, and tonno con cipolle in agrodolce, or sweet and sour tuna and onions, is one such example. A chunky sauté of meaty tuna, savory-sweet red onions and tangy wine vinegar, plus pine nuts, dried currants (or raisins), fresh mint and a small measure of red pepper flakes, this quick-cooking dish hits most, if not all, of the notes on the flavor spectrum. Firm-textured swordfish is as delicious as tuna, but since it’s best fully cooked (rather than a touch rare at the center, as for tuna), after turning the pieces, cook for about 3 minutes before transferring the fish to the plate. Salmon works, too, but make sure to use skinless fillets cut from the thick end of the fish; the cooking times for salmon are the same as for tuna.