George Lang was irked: The silk square in the breast pocket of his jacket was slightly off-tilt – and he didn’t notice right away.

“Why didn’t you tell me?” the Hungarian-born restaurateur asked, cracking a smile.

Mr. Lang, impeccable in dress and business, was getting ready to greet guests at his Cafe des Artistes, the elite restaurant he has owned for nearly 30 years. Amid murals of naked nymphs, once considered scandalous, the restaurant is a stage for both pleasure and power.

Barbara Walters and Diane Sawyer lunch there, across the street from ABC’s world headquarters. James Levine, the music director of the nearby Metropolitan Opera, eats at his favorite booth-style table, No. 33. Bill Clinton’s photo hangs on a wall, personally inscribed.

Cafe des Artistes has made Mr. Lang a fixture on New York’s social scene, involved in the arts, politics, and business. A surprise 80th birthday party last June, thrown by his wife and staff, included a broad social mix – from Howard Stern, Ruth Westheimer, and Glenn Close to Rush Limbaugh and David Halberstam.

Mr. Lang has leveraged his success into an international consultancy, working as a key player on more than 150 food-related projects. Still youthful, he’s abuzz with ideas that turn eating into entertainment.

“You have to be so excited about something new that you’d want to kill for it, so to speak,” he said. “At the same time, you can’t be so hungry for success that your survival depends on it.”

One of his current projects is working with a development group hoping to turn Beacon, N.Y., a small town on the Hudson River about 60 miles north of Manhattan, into a cultural destination. Plans call for transforming a renovated factory into a performing and visual arts complex, with Mr. Lang advising on restaurants.

Another project: the company lunchroom of the 4-year-old Conde Nast skyscraper in Times Square. Mr. Lang is the culinary brain behind the Frank Gehry-designed, multimillion-dollar cafeteria, which offers self-service food from around the world. While Mr. Lang designed a menu with comfort foods like roasted chicken, one serving station marked “global vegetarian” is lined with fare such as Japanese eggplant and curried Indian okra.

In the 1990s, Mr. Lang, with Estee Lauder cosmetics heir Ronald Lauder, revived the famed restaurant Gundel in Budapest. Mr. Lang also was a driving force behind a restaurant chain in Kuwait; the dining facilities of the Marriott hotel chain; and a nightclub and restaurant at the 1912 Manila Hotel in the Philippines, once Gen. Douglas MacArthur’s headquarters.

But it was the Cafe des Artistes on Manhattan’s West 67th Street that sealed Mr. Lang’s reputation.

The restaurant, which first opened in 1917, was shabby and half-forgotten when he took over in 1975. He renovated the nymph murals painted in 1937 by Howard Chandler Christy, created a menu that combined hearty Austro-Hungarian cooking with French elegance, and trained a staff that catered to a guest’s every whim with Old World etiquette and efficiency.

A restaurant’s success, he said, is governed by three rules.

“First, you have to do whatever you have to do to give a client two hours of happiness. That changes all the time, depending on the guests and the atmosphere.”

Second: Stay enthusiastic.

Finally, it’s about “craftsmanship. Without it, you’re nothing,” says Mr. Lang, the son of a Jewish tailor in prewar Hungary. “I learned that from my father. He was a magician. He could make a suit for someone with three humps, and make them look good.”

Mr. Lang still lives above his beloved restaurant, a clangy 1903 elevator ride away. Home is a cavernous apartment with shelves holding thousands of books on food.

There’s nothing bookish about the lived-in kitchen, complete with a dog bowl and cubbyholes where his 17-year-old son and 12-year-old daughter do their homework. Family meals are eaten on a simple wooden slab linking the kitchen and dining room. The cooking is done by Mr. Lang’s wife, Jenifer Lang, a chef trained at the Culinary Institute of America, who is the restaurant’s co-owner and managing director.

Mr. Lang arrived in America in 1946, a professional violinist carrying a dilapidated bag tied with a string, plus a few books on Greek philosophy. The Holocaust had taken 46 family members, including his parents, whom he last saw on June 26, 1944. Each year, he marks that day in his busy calendar. His eyes fill with tears as he glances at the scribbled notation: “Parents to Auschwitz.”

It’s been a rich, roller-coaster life summed up by the tongue-in-cheek title of his 1998 autobiography, “Nobody Knows the Truffles I’ve Seen.” His story takes the reader from a childhood with his mother’s slow-cooked, kosher stuffed peppers to imprisonment in a Nazi forced-labor camp to torture at the hands of Hungarian communists.

Mr. Lang turned to a career in food in the late 1940s after he heard the world’s best violinist, Jascha Heifetz; he decided to abandon the music profession for one in which “just maybe, I could be a Heifetz,” he said.

With a wry grin, he repeats the old Jewish gallows joke: “They tried to kill us. We survived. So now, let’s eat well!”