Use a mandoline slicer or a sharp knife to slice the potatoes into thin, even slices about 1/16 inch (1.5 mm) thick. Be careful when using the mandoline slicer and use the handguard to protect your fingers.
Soak the potato slices in a large bowl of cold water for 10-15 minutes. This helps to remove excess starch and results in crispier chips.
Drain the potato slices and pat them completely dry with paper towels or a clean kitchen towel. It's crucial to remove all the moisture from the potatoes to ensure they become crispy.
Preheat your air fryer to 360°F (180°C).
Spray the potato slices lightly with cooking spray, ensuring they are evenly coated.
Arrange the potato slices in a single layer in the air fryer basket, making sure they don't overlap. You may need to cook the chips in batches, depending on the size of your air fryer.
Cook the potato slices for 15-25 minutes or until they are golden brown and crispy, shaking the basket and flipping the chips a few time through the cooking time. Cooking times may vary slightly based on the thickness of the potato slices and your air fryer model.
Carefully remove the chips from the air fryer using tongs or a spatula, and transfer them to a paper towel-lined plate to absorb any excess oil. Sprinkle with salt.
Taste one chip and adjust the salt as needed. Allow the chips to cool for a few minutes before serving. They crisp up more as they cool.
Store any leftovers in an airtight container at room temperature for up to 3 days.
Notes
If you want to add seasonings I'll do it the last few minutes of cooking. I'll sprinkle on what I'd like (garlic powder, smoked paprika, chili powder...) towards the end and shake the chips to evenly coat.
I like to add the salt after the chips have finished cooking so that the salt doesn't bring up any extra moisture while the chips are cooking.
You can try skipping the water soaking step, I think it's the best way to make them but sometimes I still skip that step and we still like the end results. You can try it both ways and see if you think it's worth the effort.