Start by slicing the potatoes with a mandoline, about 1/16 inch thick. After you slice them, soak them in a bowl of water. Soak for about 30 minutes. Dry them with either a kitchen towel or paper towels.

Then cut the beets with your mandoline, about 1/16 inch thick. Add both the beets and dried-off sweet potatoes to a large bowl. Add the olive oil and salt. Mix well, coating all of the sliced vegetables.

Preheat your air fryer to 320 degrees F, air fryer setting, for about 5 minutes. Then add your vegetables so they are a single layer. You'll probably need to do several batches, depending on what air fryer you own. Flip the vegetables every 5 minutes until they are crisped up. This usually takes about 20 to 30 minutes.