I've never had Black Garlic but I'm sure it has a lot in common (taste, nutrition) with miso-fermented garlic (aka 'ninniku miso-zuke'). The miso-zuke I had was just miso and garlic, but I see you could add a little mirin:
http://www.pickl-it.com/blog/304/japanese-miso-garlic-recipe-ninniku-miso-zuke/The Elizabeth Andoh book "
Kansha: Celebrating Japan's Vegan and Vegetarian Traditions" is a great resource for Japanese style veggie ferments, including nuka zuke (rice hulls).