When the summer sun shines, it's time to cool down with something refreshing and light to keep you from melting at high noon. Enter Dr. Limón, a Peruvian slice of paradise specializing in the country's signature meal of raw fish "cooked" in lime juice. If you're a first-timer, try the "remedio casero," featuring a fresh catch of white fish bulwarked by sweet potato, choclo (large Peruvian corn), fried corn kernels, and a delicate topping of pickled onion. You could, of course, spice it up more with "Dr. Tokyo," tuna, pineapple, and hot limo pepper inside a fried tortilla chip. The dish, whose history goes back thousands of years, is a beautiful pairing of flavors, prompting Dr. Limón to have thirteen ceviche options, all as deliciously sour and fatty as the last.