Preheat your air fryer to 400°F, if your particular air fryer recommends preheating.

Remove the pork tenderloin from its packaging and pat it dry with paper towels.

Brush the tenderloin generously with melted butter, coating all sides.

Place the pork tenderloin in the air fryer basket.

Air fry at 400°F. Begin checking the internal temperature well before the end of the estimated cooking time, since cooking time can vary significantly depending on the size and thickness of the tenderloin and your particular air fryer.

Partway through cooking, carefully remove the pork tenderloin and brush it again with melted butter.

Generously season all sides with garlic and herb seasoning.

Return the pork tenderloin to the air fryer and continue cooking until the thickest portion reaches an internal temperature of 145°F.

Remove the pork from the air fryer and allow it to rest for at least 3 minutes before slicing.

Slice into medallions and serve warm.