Actually you clean it, prep it to your liking, and lay it out on cookie sheets, anything large like that, and put it in the freezer. Once frozen you just stuff it in zip locks. By freezing it on sheets you don't get chunks that never seem to be the right size.
We end up with a stupid amount of produce from the garden every fall and that is the best way to freeze it. It replicates the flash freezing you hear about in commercials.