"This recipe is especially good for those who are afraid to put fish on the grill, thinking that it will stick to it or not be sturdy enough to be cooked this way. That is not the case of tuna. The fact that you cook it as a roast, without slicing it into steaks, ensures the tenderness and moisture inside the meat. Its simply delicious! It goes great with a fresh greens salad with balsamic vinaigrette."
In a large bowl, stir together the white wine, balsamic vinegar, thyme, oregano, salt and pepper. Place the roast into the marinade, cover, and refrigerate for 4 hours.
Heat a grill for medium heat. Brush the grate with oil, once it is hot.
Place the tuna roast on the grill grate, and discard the marinade. Cook for about 30 minutes, turning frequently for even cooking. Serve immediately when the outer part flakes easily but the center is still slightly pink.