What wouldn’t he do to make an authentic cheesesteak in London, England?

When JP Teti decided to serve up Philly cheesesteaks in London, he knew nothing less than full authenticity would do.

That meant one thing: Whiz.

But in a land where people eat stuff called “toad in a hole,” wholesome Cheez Whiz seemed to be contraband.

Teti was forced underground to ensure he could fry up steaks just like the ones he remembered from his frequent childhood visits to South Philly, where he has family dating back to the 1800s.

“I started buying cases of Cheez Whiz at an American military base in Britain through a friend of mine,” said Teti, who was born in Trenton. “When questions started about those purchases, I shifted to a middleman in Amsterdam who operated on a ‘no ask, no tell’ basis.”

After the Amsterdam connection became a little too clandestine for him, Teti decided to concoct his own Whiz replacement. It took three months of experimentation to get the flavor right. Making Whiz turned out to be much more than melting down some cheese.

Then came the rolls. As any Amoroso’s-­roll-­savoring cheesesteak lover knows, even perfect Whiz cannot atone for the wrong roll.

“We went through six different bakers before we found one who could provide the texture and taste we needed,” Teti said, chuckling about how London bakers laughed out loud when he told them what kind of bread he wanted.

Then there was the matter of carving the actual steak, which just kept turning into a bloody mess. Finally, Teti purchased an industrial slicer and discovered that it’s best to freeze the meat before slicing.

When Teti felt he had mastered all the cheesesteak subtleties, he opened Liberty Cheesesteak, in March of 2014. He operates out of a truck at London’s historic Old Spitalfields Market, where his cheesesteaks quickly made a splash in a country that claims the invention of the very sandwich itself.

Customers line up at the truck for their cheesesteaks. (Linn Washington Jr./for NewsWorks)

The London Review of Sandwiches loves Liberty cheesesteaks. And, recently, a company that operates nearly 200 sandwich shops across London suddenly added a “Philly Cheese Steak” to its menu. However, the only similarity between that item and Teti’s cheesesteaks is the name.

Liberty Cheesesteak customers are as varied as Londoners themselves, ranging from lifelong  residents to Americans and other expatriates who have moved to the city and its surrounding region.

Ivor Sokolic, born in Croatia, describes Liberty steaks as “decent … much better than most British sandwiches.” Sokolic found out about Liberty from an American at his job.

Frankie Capoferri, a Hammonton, New Jersey, resident studying at the Royal Academy of Music in London, calls Liberty cheesesteaks “a little taste of home.”

A regular Liberty customer, Capoferri complimented Teti’s attention to detail. “It’s hard to get the bread right,” he said. “They nail it.”

Hammonton, New Jersey, native Frankie Capoferri is a big fan of Libery Cheesesteaks.  (Linn Washington Jr./for NewsWorks)

The idea to start this distinctly Philadelphian outpost came to Teti in the most British of locations: the public house. Over pints with friends one night, Teti began to extol the virtues of the cheesesteak and lament his difficulty in finding anything like it in London.

“I couldn’t believe that I couldn’t find a cheesesteak in this city, with such diverse foods from all over the world,” Teti said.

Now that he has remedied that situation, Teti is delighted to give his customers “a little taste of South Philly without getting on an airplane. We are trying to transfer Philly culture using cheesesteaks.”

Last summer, Teti left a job at a multi­national corporation in London, where he headed a $100 million­ division, to work full time on Liberty Cheesesteak. “Trying to split my time was a nightmare,” he said.

And he’s not finished importing classic Philly staples. He’ll soon begin offering roast pork sandwiches, hoagies and Philly­-style cannoli.

“In London, cannoli are filled with vanilla icing and they are pre­filled unlike in Philly where the shell is filled on the spot,” Teti said. “It’s all about Philly food culture.”

In a city where seemingly every fifth restaurant proclaims itself as having “the best” fish­ and chips in town, Liberty wears the undisputed crown for best cheesesteak in London.

“It is so Philly to fight your way to the top,” Teti said