Preheat the air fryer to 390 degrees Fahrenheit.
Prepare the sauce by mixing together the sesame seed oil, oyster sauce, plum sauce and hoison sauce in a small bowl. Set aside.
Place the duck on a cutting board and score the skin with a kitchen knife drawing diagonal lines. This will help render the fat and make the skin crispy.
Salt the duck on both sides.
Place the duck breasts in the air fryer basket, skin side down, and cook for 5 minutes.
Flip the duck breasts over. Turn the air fryer temperature down to 360 degrees Fahrenheit and cook for an additional 5 minutes.
Remove the duck from the air fryer, coat in the plum sauce and place in the air fryer for 1 to 2 minutes.
Check the internal temperature of the duck with an instant read meat thermometer. The USDA recommends cooking duck breasts to an internal temperature of 165°F, which will be well done.
Remove from the air fryer and let it rest for 3-5 minutes before slicing into it.