As of this writing, there really are just a few St. Louis Chinese restaurants (I mean sit-down, not take-out) that deserve mention and a visit from foodies - those in search of sweet-and-sour-chicken, beef-and-broccoli, or hot-and-sour soup can just stop reading now. But if you love Chinese food and have an adventurous palate, then I'm writing for you. With the closing of Jade Garden in 2007, St. Louis suffered a major loss from the Chinese culinary scene. One of the chefs went to Mandarin House, which now serves a menu that no longer discriminates against the non-Chinese speaking. There is no separate "Chinese menu" at Mandarin House. They have done the unthinkable and made one comprehensive menu, distinguishing "American style" dishes from "Chinese style" dishes (written in English!). I would advocate that you try and order from the Chinese style dishes. Those familiar with Jade Garden will be happy to find recognizable items on the menu.
Two other Chinese restaurants that deserve mention because I frequent them often are Joy Luck Buffet (skip the buffet) and Aseana. The saying that the good and authentic Chinese restaurants are where you will find Chinese people hold true at these two restaurants. These restaurants distinguish themselves from the ordinary Chinese cantonese style fare with a good representation of Northern cuisine and Schezuan style dishes.
These three restaurants are the ones I know best because I've eaten at them multiple times over the last 6 months. Break free from the chains of boring Kung Pao Chicken and challenge your palate!