Prepare the Marinade: In a small bowl, combine olive oil, lemon juice, minced garlic, oregano, salt, and pepper. Stir well until all ingredients are fully blended.
Marinate the Tuna Steaks: Brush or spoon the marinade over the tuna steaks, ensuring that they are coated evenly on both sides. Let the steaks marinate for 5-10 minutes to absorb the flavors.
Preheat the Air Fryer: Set your air fryer to 400°F (200°C) and let it preheat for about 3 minutes.
Air Fry the Tuna Steaks: Place the marinated tuna steaks in the air fryer basket. Air fry for 8-10 minutes, flipping halfway through, until the tuna reaches your desired doneness. A nice sear should form on the outside, while the inside remains tender and juicy.
Serve and Garnish: Remove the tuna steaks from the air fryer and let them rest for a minute. Garnish with fresh parsley and serve with lemon wedges on the side for an extra burst of flavor.