Scrub your beets and slice the ends using a sharp knife. No need to peel them. Then use a mandolin to very thinly slice the beets into chips. You want them paper thin for the best results.
Place the sliced beets in a mixing bowl and toss with the aquafaba and salt. Then arrange them in a single layer (slightly overlapping is fine) in your air frying basket, working in batches if needed.
Air fry the beet chips at 350°F/176°C for 10-12 minutes, shaking or mixing at the halfway point. The chips are ready when they've curled upwards, shrunk significantly, and feel dry to the touch. Remove them from the basket and let them stand at room temperature. They will crisp up more as they cool.
Notes
The beet slices can be slightly overlapping since they will shrink significantly, but don't stack them or overlap too much or they won't crisp up as well.The thickness or thinness of your beet chips will determine cook time and crispiness level. Slice the beets as thinly as possible, or use a tool, like a mandolin for easy slicing.The chips are ready when their edges have curled, and the slices feel dry to the touch. Do not overcook the beet chips or they will have a bitter taste. They will crisp up a little more after you remove the basket from the air fryer and let the chips cool.