Here is a really delicious recipe from my friend Lynne Kasper. Lynne spent many years researching RECIPES FROM EMILLA-ROMANGA, THE HEARTLAND OF NORTHERN ITALIAN FOOD. Her book THE SPLENDID TABLE should be a part of every good cooks library.
Heat the olive oil in a heavy 12-inch saute pan over medium-high heat. Add the fish steaks in a single layer, sprinkling the onion and parsley over and around them. Sear the fish for about 1 minute per side so the flesh whitens and tightens. Turn the heat down to medium low. Scatter the basil, garlic and 3 Tbs. of the wine around the fish. Sprinkle lightly with salt and pepper.
Keep the fish uncovered as you cook it 2 or 3 minutes more per side, or until still soft enough to have just a little give when pressed. If in doubt, slit into the center of a piece, checking that the meat is opaque but not dry or flaking.
Transfer the steaks onto a heated platter. Turn the heat up to high, and add the remaining wine to the saute pan. Boil for about 30 seconds, scraping up any brown bits in the pan. Add the tomato and olives, and toss 20 seconds over high heat. Spoon the sauce over the tuna, garnish with more basil and serve.