Wash potato, peel, cut into large chunks, adding chunks to a large bowl.
Add 1 teaspoon of oil to the bowl of potato chunks and just using your clean hands, toss well until all surfaces are coated. (Tip! first have air basket pulled out and beside you, ready to receive the potatoes, because your hands will be oily.)
Cook (no need to pre-heat) at 160 C (320 F) for 25 minutes.
Take out the potatoes and tip them back into the bowl you have been using. Toss them in there briefly and gently using a large spoon.
Transfer potato chunks back into fryer basket. Place back into machine, raise temperature on the machine to 180 C (350 F), and cook for another 7 minutes.
Take out the potatoes and tip them back into the bowl you have been using. Toss them in there using a large spoon. (At this point, a few might look just about done, but once you toss them you'll see that there's loads that aren't quite as far along.)
Transfer potato chunks back into fryer basket. Leave temperature unchanged. Roast for a final 7 minutes.
Serve piping hot. Best reheated in machine.
Leftovers are best reheated in the air fryer as well, to restore their crispness to them. Try about 3 to 4 minutes at 160 C (320 F).