Preheat Air Fryer to 400˚F.
Remove pork tenderloin from the fridge about 15 minutes before you are ready to cook it.
Pat dry the pork tenderloin with paper towels.
In a small bowl whisk together the mustard, olive oil, oregano, rosemary, garlic powder, onion powder, smoked paprika, salt, and pepper.
Spread the mustard mixture all over the tenderloin.
Spray the air fryer basket with oil and place the tenderloin in the basket. If needed to fit, bend it or cut the tenderloin in half. Grease the top of the tenderloin with cooking spray.
Cook for 10 minutes; flip, lightly grease with cooking spray, and continue to cook for 10 to 14 more minutes, or until the internal temperature of the pork registers at 145˚F. See my Notes below.
Transfer cooked tenderloin to a cutting board and let stand for about 5 to 8 minutes before cutting.
Cut and serve.