Many Vietnamese strongly deny any French influence on their national dish, arguing it pre-dates the colonial period and is uniquely northern Vietnamese.

But whatever the real story, “pho is one of the world’s best soups,” Corlou said. “For me Vietnamese cuisine is the best in the world.”

Corlou said that while the main ingredients of pho stay constant, the dish must evolve.

At his three Hanoi restaurants, for example, he offers a salmon pho as well as a pho au fois gras priced at $10 a bowl — “you cannot put pho in a museum,” he said.

In the last decade, new local versions of that classic — including fresh rolls made from unsliced pho rice noodle sheets — have also emerged.

And as Vietnam has grown richer, more expensive pho — including a reported $40 kobe beef version — has appeared.

But beyond adding more meat, there is not much you can do to improve the dish, said Hanoi-based chef and cuisine expert Tracey Lister, who thinks the Vietnamese deserve the credit for their acclaimed noodle soup.

“It is the great dish, the celebrated dish, and I think we’ve got to let Vietnam have that one,” Lister, the director of the Hanoi Cooking Center, said.

“Pho truly represents Vietnamese cuisine. It’s a simple dish yet sophisticated. It is a very elegant dish. It’s just a classic.”