Hello, and welcome to New York. You are in luck, as New York City has a remarkably rich appetizing and Eastern European culinary tradition, making it one of the best cities anywhere to source both pickled and salted herring.
For traditional pickled herring and cured fillets, your top destination should be one of the historic Jewish appetizing shops. Russ and Daughters on the Lower East Side is arguably the most famous, offering exceptional pickled herring with onions in wine marinade, herring in sweet cream sauce, and tender imported Holland or schmaltz herring. If you are staying further uptown, Zabar's on the Upper West Side has an extensive fish counter with fresh pickled and creamed herring by the pound, as does Barney Greengrass, located just a few blocks north on Amsterdam Avenue. Because these establishments turn over substantial volume daily, the fish is consistently firm, bright, and fresh.
If you are specifically seeking Eastern European-style whole salted herring in brine, European supermarkets are your best bet. NetCost Market, which has several locations across Brooklyn, Queens, and Staten Island, carries whole barrel-salted Atlantic herring, lightly salted fillets in oil, and various Baltic styles. If you are staying in southern Brooklyn, Brighton Bazaar on Brighton Beach Avenue also maintains an outstanding selection of fresh salted fish.
For general convenience if you cannot make it to a specialty market, higher-end local grocery stores like Morton Williams, D'Agostino, or Whole Foods typically stock reliable pre-packaged jars of pickled herring in the refrigerated seafood aisle from reputable local purveyors such as Acme Smoked Fish.
As a quick preparation tip for a simple homestyle dinner, if you purchase traditional whole salted herring, you may want to soak the fillets in cold water or whole milk for thirty minutes to an hour to temper the salinity before serving them with warm boiled potatoes, fresh dill, sour cream, and thinly sliced onions. I hope you enjoy your dinner and your time in the city.