In a small bowl, mix together all of the dry rub spices together until well blended; set aside.
In another small bowl, mix together all of the maple mustard sauce ingredients until combined; set aside.
Preheat the air fryer to 400º F.
Put the pork tenderloin onto a clean cutting board. Gently pat it dry with paper towels, then rub it down with a bit of olive oil on all sides.
Sprinkle the dry rub over the pork tenderloin and rub it all over, making sure it's even and that all sides are coated.
With tongs, place the pork tenderloin into the air fryer and cook it at 400º F for 10 minutes.
After 10 minutes, open the air fryer and brush a generous amount of maple mustard sauce over the top and sides of the tenderloin. Cook it for another 5 minutes, then open the air fryer and check the internal temperature. If you're around the 130-135º F mark, slather more maple mustard over the pork and cook it for another two minutes. I remove the pork when it's close to 140º F because it will continue to cook as it rests, bringing you to the desired internal temperature of 145º F.
When done, carefully transfer the pork to a clean cutting board or serving dish. Let it rest for 5 minutes before cutting into it.
Slice the pork into medallions and serve with a side of maple mustard sauce; sprinkle with some fresh herbs if you want.