Preheat your air fryer to 160℃, pat the skin of the duck legs with a kitchen towel to remove excess moisture. Prick the skin and season with salt and black pepper, if desired.
Place the duck legs skin side up in your preheated air fryer for 30 minutes.
When the 30 minutes is up lift the duck legs out of the fryer and place on a plate. Put the par boiled potatoes into a bowl and pour the duck fat from the base of the air fryer over the potatoes. Season them with salt and mix. Place the potatoes in the bottom of the air fryer drawer and place the duck legs on top.
Turn up the air fryer to 180℃ and continue to cook for 20-30 minutes until the potatoes are golden and crispy.