A few of us are coming for a conference, staying around Union Square. We love good food, but coming form the Midwest, we are not used to paying outrageous sums for it. So, chowhounds, please share your wisdom. Here are some parameters: don't mind taking a cab, but prefer public transit if it's not walkable. Cheap means entrees in the 15 to 25 range. Chinatown recommendations would be appreciated. (We did already book one dinner at Aziza.) Thanks, in advance, and I apologize if this replicates some prior posting -- my chowhounds search skills aren't great.