New Belgium Brewing Company: Clutch

Official description from the brewery:
It started as chance, a sandwich shop encounter between a band and a fan. It ended as the Clutch Collaboration. This pleasing, two-part potion was brewed with chocolate and black malts for a rich and roasty overtone, then fused with a dry, substratum of sour for a bold and audacious flavor. Black as night, this beer is blended at 80% stout, 20% dark sour wood beer for a collaboration that begins with a sour edge and finishes with a big, dark malt character, lingering, sweet on your palate. The two flavors come as raucous and riotous as the Maryland band and their Fort Collins fans, getting loud and making beer, together.