Make the teriyaki marinade. Whisk together soy sauce, honey, rice vinegar, mirin, minced ginger, minced garlic, and sesame oil in a bowl.
Prepare the pork. Remove the silver skins of the pork tenderloin. Then, fork the meat to let the marinade seep deeper into the pork.
Marinate the Pork. Place the pork tenderloin in a resealable plastic bag and pour the teriyaki marinade over it. Seal the bag and massage the marinade into the pork. Let it marinate in the refrigerator for at least 30 minutes (or overnight for a more intense flavor).
Preheat your air fryer to 400ºF (204ºC) for about 5 minutes.
Air fry marinated pork tenderloin. Remove the tenderloin from the marinade and let any excess marinade drip off. Place the marinated pork in the air fryer and cook for 20 - 25 minutes at 400ºF (204ºC). Flip halfway through.
(Optional) Create a teriyaki glaze while the pork is air frying. Place the remaining marinade in a saucepan and boil over high heat, reaching 212ºF (100ºC). Cook for 5 minutes or until thickened before removing it from the heat.
Insert a meat thermometer into the thickest part of the pork. The internal temperature of the pork should reach 145ºF (63ºC). For well-done pork, cook it a few minutes longer until the internal temperature reaches 160ºF (71ºC). Once it reaches your desired temperature, remove it from the air fryer.
Once cooked, remove the pork from the air fryer and let it rest for 5 - 10 minutes before slicing.
Slice the pork tenderloin into medallions and brush them with the thickened teriyaki glaze.
Serve and enjoy the air-fried marinated pork tenderloin with steamed rice, stir-fried vegetables, or a side salad. Then, garnish with sesame seeds and/or chopped scallions.