Prepare the Steaks: Pat the steaks dry with paper towels to remove any moisture, which helps achieve a crispy sear.
Season: Rub olive oil over both sides of the steak. Season generously with salt, black pepper, and garlic powder, if desired.
Preheat the Air Fryer: Preheat your air fryer to 400°F (200°C) for about 5 minutes to ensure even cooking.
Cook the Steak: Place the steaks in the air fryer basket in a single layer. Cook for 10-12 minutes, flipping halfway through. For medium-rare, aim for an internal temperature of 130-135°F; adjust cooking time based on desired doneness.
Add Butter: When the steak is nearly done, place a small pat of butter on each steak. Close the air fryer and let it melt over the meat in the final minute of cooking.
Rest and Serve: Remove the steaks from the air fryer and let them rest for 5 minutes on a cutting board to retain juices. Slice against the grain, garnish with fresh rosemary or thyme, and serve warm.