I just checked with dh (butcher), as the word says you would be grinding it and it comes out through the plate at the end and is extruded out into the shape of the holes through the plate. I use to do the mince all the time through an electric one at the shop and a lot of meat gets stuck in the 'worm' before it gets extruded out. So a long story short - grate it by hand. Even the hand ones get meat caught in the middle, so soap would also. We have a hand one here at home and I wouldn't bother. One thing in its favour it would be easy to wash up.