Wash the potato and peel the skin. (I like to peel the skin for the better look of the chips, but you can leave it on if you prefer.)
Slice the potato into thin rounds using a mandolin slicer or a sharp knife. Aim to cut them about 1/8 inch thick.
Soak the potato slices in cold water for about 30 minutes. Then drain and rinse them a couple of times to remove the starch.
On a flat surface, place a layer of paper towel, and then place the potato slices on top in one single layer. Add another layer of paper towel to dry the potato slices. Let them sit for 10 to 15 minutes until the slices are completely dry.
Preheat the air fryer to 300°F (150°C). It usually takes about 3 minutes to be ready.
Spray cooking spray on both sides of the potato slices. Add the potato slices to the air fryer basket, trying to spread out evenly. (If you cook more than 1 potato, cook them in batches, and only add about 30 slices at a time)
Set the timer to 16 minutes. After 8 minutes, take out the basket and gently shake the chips. Use tongs to separate any chips that are stuck to each other.
Put the basket back, and after another 8 minutes, take out the basket again and shake.
Now increase the temperature to 400°F (200°C), and set the timer to 5 minutes. Put back the basket. Watch very closely, and check every 2 minutes until the chips are crispy and golden around the edges. If there are only a few chips with soft centers, put them back and cook for 2 more minutes.
Sprinkle with salt or the seasoning of your choice.