Start by patting your tri-tip dry with paper towels to help the seasoning stick better.
In a mixing bowl, combine the olive oil, salt, dried oregano, garlic powder, onion powder, black pepper, paprika, and cayenne pepper (if using). Stir until well mixed.
Rub the spice blend all over the tri-tip, ensuring every inch is covered. Let it marinate for at least 30 minutes.
Preheat your air fryer to 400°F (200°C) for about 5 minutes.
Place the seasoned tri-tip in the air fryer basket. Cook for about 25-30 minutes, flipping halfway through, until the internal temperature reaches 135°F (57°C).
Remove the tri-tip from the air fryer and let it rest for about 10 minutes before slicing against the grain.