Preheat the air fryer to 400 degrees F for a couple of minutes while you prep the potatoes. In a small bowl combine wholegrain mustard, olive oil, garlic, salt and pepper. Stir to combine. Pour the olive oil mixture over the potatoes and mix to coat the potatoes evenly. Add potatoes to the preheated air fryer and cook for 10 minutes at 400 degrees F. Shake the basket then cook for an additional 10-15 minutes at 400 degrees until potatoes are cooked through and golden brown. Season with salt while hot and give the basket a shake. Serve and garnish with fresh parsley if desired. Enjoy!