As long as it's very fresh, tuna can be served a little rare in the middle. This is ideal for tuna steaks as the fish has a tendency to dry out if cooked for too long. One-inch thick tuna steaks can be perfectly cooked in about 10 minutes. Much like a good sirloin or quality beef steak, tuna suits grilling or shallow frying in very hot oil. Use a marinade for extra moisture and to add flavor to the fish.
Wash both one-inch tuna steaks in fresh water to remove any scales or other debris. Lay both on a paper towel. Cover with another paper towel to soak up the water.
Drizzle 2 tbsp. of olive oil into a small bowl. Grind pepper and coarse salt to taste. Add a pinch of garlic salt and a pinch of dried onion powder. Add a little cayenne pepper if you like a hot kick to your grilled fish.
Coat each tuna steak in the oil marinade, rubbing it into both sides and the edges of the fish.
Spray or brush a large griddle pan with olive oil. Heat the pan on the stove for about two minutes or until it reaches medium to high heat.
Gently lay each tuna steak on the hot griddle pan. Let the fish sizzle and don't move it around in the pan. Cook for only 2 minutes on the first side for a rare steak, or 5 minutes for a medium.
Turn the steaks and cook for the same amount of time as you cooked the first side. This ensures that the tuna steak is cooked evenly and seared well on both sides -- particularly important with chunky one-inch steaks.