Preheat air fryer to 400°F for 5 minutes.
Whisk 1 tablespoon brown sugar, 2 teaspoons mustard, 1 teaspoon vinegar, ½ teaspoon garlic powder, ½ teaspoon onion powder, ½ teaspoon paprika, ½ teaspoon salt and ¼ teaspoon pepper together in a small bowl.
Pat 1 pound pork tenderloin dry with paper towels. (If using a small air fryer, cut the pork in half crosswise.) Rub the spice mixture onto the pork and place in the fryer basket.
Cook until an instant-read thermometer inserted in the thickest part registers 145°F, 15 to 18 minutes.
Let rest for 5 minutes before slicing.
