Letting water come into contact with your oil is one of the biggest pitfalls to avoid when deep-frying. As Taste Of Home explains, too much moisture on the outside of your food can cause your oil to pop and sputter, and that moisture can also prevent the outside of your food from getting crispy, which is probably half the reason why. you fry it in the first place. Any amateur chef who has tried deep-frying for the first time is probably familiar with the terrifying crack of an under-dried chicken wing or a slice of zucchini hitting the oil. Those hot, greasy drips shooting out of your pan are dangerous and can cause serious burns.
But where does this moisture come from and what does salt have to do with it? Salting your food before frying removes moisture through the process of osmosis (via PopSci). If you salt meat or vegetables and let them sit for a few minutes, you will likely notice water droplets on the outside. That’s your salt in action. So unless you want to wipe oil residue from any surface around your stove, wait with the salt until your food comes out of the fryer.