Zucchini is a naturally soft vegetable once cooked due to its high water content. While the combination of the panko breading and air frying method give it a nice crispy crust, you can make the zucchini a little less soft if that's your preference. Instead of adding the salt to the panko mix, sprinkle it over the zucchini slices and let it sit for about 10 minutes. This will pull out much of the moisture and help it remain firm while air frying.