Wash and slice the zucchini into thin rounds, about 1/4 inch thick.
Lay zucchini on a paper towel lined sheet pan and sprinkle with salt. Let set for 30 minutes to draw out the moisture. Pat dry, removing as much liquid and salt as possible.
Heat a 1/4-1/2 inch of oil in the bottom of a large skillet over medium heat to 375 degrees.
Beat together the egg and water in a shallow bowl.
Stir together the coconut flour and Parmesan in a second shallow bowl.
Coat the zucchini in the egg and then dredge in the coconut mixture to coat.
Add a single layer of zucchini to the hot oil, being careful not to crowd the pan. Fry for 1-2 minutes on each side, until golden brown. Repeat with remaining zucchini.
Drain on a paper towel lined plate. Sprinkle with salt, if desired.
Serve with ranch dressing for dipping.
Salting and letting the zucchini sit to draw out moisture is optional if you're in a hurry, but it does make for a crispier crust on the zucchini. You can add seasonings to the breading, such as onion powder and garlic powder, if desired. We dip ours in ranch dressing when eating and find the zucchini doesn't need additional seasoning as the Parmesan also adds flavor.We have not tested this in the air fryer, but if I were testing I would start at 390 degrees for 6-8 minutes and see how it goes.