If there’s one restaurant on Long Island you don’t expect to be surprised by, it’s Louie’s Oyster Bar & Grille. The Port Washington stalwart, which started life in 1905 as a barge in Manhasset Bay, has stood on its waterfront perch for more than 50 years, serving a menu of American seafood classics.

But Louie’s — now, formally, Louie’s Grill & Liquors — has hired an accomplished new chef who, in turn, has completely revamped the menu.

The chef is Tomo Kobayashi, a Japanese native whose passion for French food led him to the New York kitchens of Christian Delouvrier’s renowned restaurants Lespinasse and Alain Ducasse at the Essex House, as well as Gabriel Kreuther’s Atelier in the Ritz Carlton. He came to Long Island in 2007 to open the Poll Brothers’ Toku Modern Asian in Manhasset and, in 2013, he became corporate executive chef of the whole Poll empire (Toku and Cipollini in Manhasset, Hendricks Tavern and Bryant and Cooper in Roslyn, Bar Frites in Greenvale). In 2015, he left fine dining to open the short-lived Yatai Casual Asian in Mineola.

With its extensive waterfront deck, Louie’s has long been a warm-weather favorite. But owners Martin Picone and Mike Guinnane, who bought the place in 2002 from its original owners, the Zwerlein family, wanted to make it a year-round destination. Soon after Kobayashi came on board, they realized that asking their new chef to keep churning out clam chowder, lobster bakes and fish and chips would be like buying a racehorse to pull a plow.

Not that Kobayashi has abandoned seafood. There’s still a raw bar where you can get local clams and oysters and shrimp cocktail. The menu includes clam chowder, lobster roll (albeit with tarragon mayonnaise, bibb lettuce and house-made chips) and a steamed lobster with corn on the cob — as well as more inventive dishes such as clam pizza with pancetta, miso black cod, lobster Cantonese, steamed sea bass rolls (a variation on a Toku dish) and sole en papillote with fennel, zucchini, carrots and hon-shimeji mushrooms.

Fish makes up about half the new menu. Land-based selections include steamed edame dumplings (a favorite at Yatai), beef short rib lettuce cups with chimichurri, Thai steak noodle salad, fried chicken sandwich and Berkshire pork chop with roasted Brussels sprouts.

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Right now Louie’s seats more than 330 diners. Kobayashi said that work would start soon on a roof deck that would accommodate even more.

Louie’s Grill & Liquors is at 395 Main St., Port Washington, 516-883-4242, louiesoysterbarandgrille.com