Old thread is old and I'm guessing that the OP with 10 posts in nearly 4 years probably won't read this but:
I just had an idea! Ask the wait staff what the sauce is called next time you're in there.
To me it sounds like the Duck Sauce that comes with Chinese takeout, which I consider the most useless sauce ever invented. It's a "slightly" sauce; It has a slight flavor, with the slightest hint of citrus and sugar, and is slightly thickened with some kind of starch.
But mostly it tastes like nothing.