I got this tip from a nonagenarian cousin, so you know there's a depth of experience behind it:
Standing Room Only
635 75th Street
It may be small, and it sure looks modest, but I understood from the first bite what she was talking about. My brat had grilled onions on it and the result was ... amazingly subtle, in the best possible way.
If you find yourself in the neighborhood and your appetite runs this way, go for it!