I didn't know, but it took me all of 5 seconds to find out. Next time try looking a little harder.

Yirgacheffe Coffee Farmers Cooperative UnionNow that I'm done razzing you, here's a good article on the subject:
The Nation's Champion Barista Makes it Look Easy (NYTimes). This sounds delicious:
Katie Carguilo wrote:My sig bev was inspired by the fermentation of coffee.
When a coffee is washed, the seeds are removed from the ripe cherry after picking, but they don't come out completely clean, much like the pit of a nectarine wouldn't come out completely clean, and in fact, I pitted a nectarine onstage to demonstrate this. There's still some fruit pulp stuck to it that has to ferment before it has broken down enough to be able to be washed off before the coffee beans are dried.
Each region has their own tradition or practice for doing this, but in Yirgachaeffe they ferment the coffee underwater for 48 hours. Over this time, that water changes from dissolving the coffee pulp to yeast activity creating carbonation and vinegar.
It was this flavor that I tried to recreate as the base of the signature beverage. I used a mash of nectarine, lemon, jasmine green tea and vinegar, and topped that with the Haru espresso and served it in a Riedel grappa glass. I chose that flute because Ethiopian coffees are, to me, the champagne of the coffee world: Coffee is only indigenous to Ethiopia — it was carried by hand and planted everywhere else it now grows, so one could make the argument this is the only place true coffee exists.