Diagonally score the top of the steaks 1/8-inch deep, and repeat the opposite way to create a diamond pattern.
In a freezer bag, combine the flank steak, 3 tablespoons of oil, lime juice, cumin, garlic powder, and salt. Add the flank steak and marinate at least 2 hours or up to 12 hours.
Remove the steaks from the marinade and discard the marinade. Gently pat the steaks dry with a paper towel.
Brush with oil and season with ½ teaspoon additional salt if desired.
Preheat the air fryer to 400°F. Place the steak in the air-fryer basket and cook for 10 to 15 minutes or until the steak is browned and reaches 130°F for medium rare or 140°F for medium.
Let the steak rest for 5 minutes and cut across the grain.