how to make crystallized ginger powder I make chocolate bonbons and in my new recipe I am trying to make a ginger ganache topped with dark chocolate. (This is the easy part).

The hard part is when you think about a new shape for it. So what I want is to put on top of each bonbon, little of crystallized ginger, where they look like sea salt flakes.

I don't know how to do it, but I saw it in a chocolate shop, long time ago where they sprinkle it on some bonbon.

I finely grated the ginger but now the weird part of how should I crystallize them. Do I just add sugar on, and leave them a few hours ?
The normal way of making crystallised ginger is to boil 1-cm cubes or slices of ginger briefly in water a couple of times to get rid of the bitterness, then simmer it for a long time in syrup. Once it's nice and soft, you drain off as much of the syrup as possible, then coat the pieces in granulated sugar. 

If you have already grated it, I guess you could still use the same method, but you wouldn't need to simmer it in syrup for so long, and draining the syrup off might be a challenge. If you add enough sugar, it will eventually absorb the remaining syrup, and I am sure that the surplus (gingery) sugar won't go to waste!