I am still not convinced. With a ball mill, charcoal can be reduced to any required mesh size with very little mess providing care is taken and the egress of said product is conducted outdoors.
There are no compatibility problems relating to charcoal that I am aware of, perhaps with the exception of the cocoa type blackpowders.
I much prefer my onions in a salad or a nice French onion soup! Much less hard work too!
Not to mention the raw material for charcoal is gathered in large quantity much more easily, and generally for free. Even if this onion formula had some useful, practical purpose, I doubt it'd be worth sitting around a few hours peeling onions just to recover a few tens of grams of material. And that's effort put in before the hassle of grinding it down, so I don't see how it's supposed to be any less effort or hassle than charcoal...
Still, this thread gets top marks for hilarity, however unintentional.