Why Dry Before You Fry?

Why do we remove moisture from the surface of food before we fry it?

There are at least two reasons.

First, unless you want an explosion of hot oil in your kitchen, tossing wet things into hot oil is a bad idea. When water is put into hot oil, it vaporizes almost immediately - and that vapor wants to escape. It doesn't care if it takes some oil with it when it does, or if that oil ends up all over your stovetop (or, even worse, you). Vaporized water is unfeeling that way.

Second, when water is put into hot oil, it vaporizes almost immediately - and that vapor wants to escape.. Wait. I said that already, right? Here's another aspect of that, though: when the water vaporizes, it is absorbing heat from the oil. When it escapes, it takes that heat with it. The net result is a drop in the oil's temperature (which is already dropping because it is being absorbed by whatever food you put in there to cook). Inefficiencies abound.

Oh, yeah. Also, water vapor = steam. When you drop something wet into hot oil, you end up steaming it a bit. That's not generally what you're going for when you set out to deep fry something.