A few points after reading all of this:
1) Xiao Sichuan is the most authentic Chinese food I've found in MN thus far. The Tea House (well, the one in Plymouth) doesn't come close to it. I haven't been to Tian Jin yet, but I'm heading there soon.
2) Stop pretending that the Chinese restaurants in NYC are so great. There are probably only two (Da Sichuan and the Shanghai Cafe) that are any better than the typical American Chinese food. Any other cuisine in Manhattan would blow MN away (Korean, Japanese, etc.), but Chinese...not so much. LA and SF have much better Chinese food than NYC. I don't know why -- they just do.
3) What is "Mandarin" cuisine? Mandarin is a language.