In New York, they call it crudo, but here at da Claudio Pescheria dei Milanesi, they call it sushi. Go figure.
Plus, rather than fetching the high prices you'll find in New York for Italian-style raw fish, at da Claudio you can have yourself a generous plate full of ultra-fresh thin-sliced fish, including tuna, salmon, shrimp, and branzino, among other varieties, for just 10 euros (and that's including a glass of wine).
You do have to eat standing up, but that's part of the fun. It's cheap, unpretentious, and delicious.
The blog Porcini Chronicles compares the sushi servers to baristas, and the comparison is a good one. Like ordering un caffe at a bar, you pay first at the register, then head to the counter, which is set smack dab in the middle of the fish shop, and present your receipt. The barista (or pescerista, if you will) lays down a pile of chopped salad on plate, covers it with raw fish, ladles on deep green olive oil, and dusts the whole thing with sea salt and black pepper (there's also a selection of marinated seafood like cuttlefish, shrimp, and scampi to choose from, along with raw oysters and other shellfish).
An order includes a glass of sparkling white wine poured from a tap. The pesceristas work quickly, and the pace is frenetic, particularly during lunch. But, once you get your order and can settle in to the tender fish, crunchy salad, and cheap, but refreshing wine, you can just relax and enjoy the show.
da Claudio Pescheria dei Milanesi
16, Via Ponte Vetero