The only decent restaurant on the Plaza de Armas is this second-floor perch with a vaguely Alpine air that flirts with Peruvian and international food and is a good place to head if you're fed up with chicken (easily done in Peru). They do good sandwiches, creative crepes, Thai curry, trout with almonds, and interesting things with quinoa.
The giant murals add welcome color, but the real star is the square outside. Grab a window seat and enjoy it over a pisco sour.