Preheat the air fryer: Set it to 380°F (193°C) for 3–5 minutes. A hot basket helps sear the outside fast.
Pat off frost: Unwrap the frozen tuna steaks and blot any surface ice with paper towels.
This helps oil and seasoning stick.
Oil and season: Brush both sides with oil. Sprinkle with salt, pepper, garlic powder, and paprika. Press gently so it adheres.
Air fry, round one: Place the steaks in a single layer in the basket.
Cook for 5 minutes at 380°F.
Flip and check: Flip the steaks. If using sesame seeds, sprinkle now. Air fry another 3–5 minutes, depending on thickness and desired doneness.
Gauge doneness: For rare to medium-rare, the center should be deep pink and warm.
An instant-read thermometer inserted sideways should read around 95–105°F for rare or 110–115°F for medium-rare. For medium, aim for 120–125°F. Keep in mind the temp will rise a few degrees as it rests.
Rest the tuna: Transfer to a plate and rest for 2–3 minutes.
Squeeze with fresh lemon or lime for brightness.
Serve: Slice across the grain and plate with a simple salad, steamed rice, or roasted veggies. A drizzle of soy-lime or a quick wasabi mayo is great here.