Just got back from Cocina Cuzco, on 7th Ave, and I was very impressed with it. I haven't had much in the way of Peruvian food in the past, so I can't vouch for its authenticity and such, but it was very good. We were in the mood for something light, so just had soups and salads, but the rest of the menu looked very good as well.
I had a seafood soup, don't remember the name, but it had shrimp, scallops, mussells, clams and lots of squid in it, as well as some corn, peas, green beans, rice, lime, and green chili - excellent. The black bean soup was good as well, as were the salads, and the mojito really hit the spot.
I was also very impressed with the service - genuinely friendly waiters, whose upsell attempts didn't come off as obnoxious, and who noticed that one of the salads wasn't finished and asked to make sure everything was OK.