Calling ceviche “raw fish marinated in citrus juice and spices” is a bit like describing the Taj Mahal as a marble building. Technically correct, but missing the point. Because ceviche, enjoyed across South America, but particularly worshipped in Peru (they actually celebrate National Ceviche Day on June 28) is almost magical. It uses super-fresh fish, and the citrus marination, barely 30 minutes, is what breaks down the fish proteins, giving the raw flesh a cooked flavour but retains its delicate taste. Good ceviche typically has crunch: Raw red onion, coriander, toasted corn, and creamy avocado or sweet potato, all sliced...