It's not in Chinatown, but it's 1 block from my house, a
GNR, and cranks out delicious duck.
As far as preparing it, they're fully cooked so just slice and eat. Definitely make it clear if you want the duck whole or cut up (which will be artfully hacked with a cleaver, bones and all).
-Dan
Sun Wah BBQ
5041 N. Broadway
773-769-1254
Chicago, Illinois 60640