Rinse and pat tuna steaks dry. Place zest on top of cutting board. Pile rosemary and parsley leaves on top of zest. Pile garlic and some coarse salt and black pepper or grill seasoning on top of herbs. Finely chop the garlic, herbs, and spices. Drizzle the olive oil over the tuna steaks just enough to coat each side. Rub herb and garlic mixture into fish, coating pieces evenly on each side. Let stand 10 minutes.

Grill tuna steaks 6 minutes on each side or 4 minutes on each side, if you prefer pink tuna at the center. Cook steaks over: high setting on indoor electric grill, medium high heat on outdoor gas grill or, 6 inches from hot, prepared charcoal.