As stated above black garlic tastes entirely different from fresh garlic. It isn't a variety and isn't a substituted for fresh. It's black from being heated low and long until it becomes like a sticky, smokey, sweetish, garlicky paste. Delicious.

I have no idea how it can be ground because it is so moist and sticky. I'd be suspicious that it was further processed in some way to make that possible.

It is much used by Yotam Ottolenghi. Google his name and 'recipes' and you'll find a lot of ideas.

I have tried making BG in my old-fashioned range which stays warm all the time. It was ok but not as good as the commercial stuff.