I'm not sure if your concert was tonight.
There is a Czech restaurant on Cermak right off or Harlem, called, I believe, Czech-American Inn. It's a bit closer to River Forest than Klas which is way down Cermak, actually in Cicero. I have never been to Czech-American Inn, but I have heard good things about it, in that cheap Chicago Bohemian style of dining way.
I wonder if there is any restaurants in River Forest besides the beef place Annie's and River Forest Grill (and Pannera). Oh, and the crappy Pronto Roma. To paraphrase David Hammond, the best dining in River Forest is in Forest Park. I am always happy at Jimmy's, the bar-restaurant on Madison. I am not *always* happy with Yum Thai, a bit west on Madison, but when it's on, it's very good. As I've warned many a time, ask for the translated menu.
I recently tried the new Penny's in Oak Park, just across the street from River Forest. I was very hungry an hour later, although the dumplings were not that bad.
There's always a, now famous, Big Mickey.
Rob