Any of the five boroughs will do!
I've been eating these for the last 18 years or so, I'm 22 now and I still don't know the official chinese name. I feel embarrassed asking such gourmands here!
I ate some the other day at a place on grand st. don't remember the name of the place, it was right by the grand street shuttle train and was mentioned in new york magazine. it sells dumplings wholesale, and my steamed buns were 3 for 1.80. filling to boot!
just other suggestions, I love trying new places.