Put your stove top grill ir skillet on at medium high and spray or swab with oil. Put the steaks in a shallow bowl and drizzle with olive oil. Turn them over so that each side is coated with the oil. Lightly sprinkle both sides with salt, pepper, garlic powder and dried dill leaves. You could substitute dried oregano if you are caught without the dill weed. If you want to you could go further at this point with lemon zest or cyanne pepper and on and on but stopping at the dill weed or oregano works real good.
After you set them on the grill. Don't move them until you think it might be time to turn them over because they might want to stick before they start to get grilled. For rare or raw in the middle grill about 1 - 1 1/2 minutes a side. We like ours medium and we give them 2 1/2 - 3 minutes per side.
Serve it with a lemon wedge and drizzle it with lemon juice just before you enjoy it. A good chilled white wine like a Pinot Grigio or a Chablis would go real well with your Grilled Tuna Steak. Enjoy!