At lunchtime on a street near the Gare du Nord in Paris, queues were forming at a fast-food restaurant. Construction workers jostled with schoolchildren for what has become a business phenomenon: the hefty, cheesy slab of indulgence known as the French taco.

France has always had a huge market for takeaways, from kebabs to McDonald’s, and fast food accounts for more than half the nation’s restaurants. Now the homegrown French taco is challenging the burger’s imperialist success and plotting its own global expansion.

The French taco, which bears little resemblance to anything Mexican, is a cross between a grilled panini, wrap and kebab, with everything sealed inside a vast rectangular parcel – fries included. There is often a pile-up of different meats jostling together, such as chicken nuggets and merguez sausage, and several sauces. It was described by one French food writer who couldn’t finish one as a “hymn to junk food”.

The market leader, O’Tacos, is expanding in France at a rate faster than McDonald’s and has come to symbolise the entrepreneurship of France’s low-income banlieues. Started by three former school friends in the working-class outskirts of Grenoble, the chain is now so popular among 15- to 25-year-olds that politicians in small towns increasingly seek out franchises to boost deserted high streets.

Opening events and appearances by rap stars often attract large crowds, and diners get their money back if they manage to finish a Gigataco, which weighs several kilos. With more than 200 outlets in France, as well as franchises in Belgium and Morocco, the chain has a global turnover of more than €200m a year. A Belgian investment fund has come onboard to push international expansion.

The exact origin of the French taco is shrouded in myth, but it is believed to have been born 15 years ago in a kebab shop on the outskirts of Lyon as an experiment in combining a kebab and a wrap.

Patrick Pelonero, the co-founder of O’Tacos, was a builder in Grenoble in 2007 and looking for a way to make some money in the slow Alpine winter months. With his friends Silman and Samba Traoré, who are brothers, he created a product that was halal and where the customer can choose their own combination of a bewildering number of fillings held together with French cheese sauce.

“It’s a take on the traditional sandwich – tortilla, shawarma, whatever you like to call it – and it’s easy to eat,” Pelonero said. “Everything is inside, it’s clean, nothing drips on you, the meat doesn’t fall out the side.”

Facebook Twitter Pinterest A queue outside an O’Tacos restaurant. The chain is popular among 15- to 25-year-olds. Photograph: PR Company Handout

Pelonero, who invented the cheese sauce after months of trials in his kitchen, said: “It was all intuitive and quite natural, it wasn’t pre-planned and I think people feel that. We did what we want, we followed no rules. We were lucky.”

He said the business was also about creating a meeting space for young people in poorer suburbs away from city centres. “It’s the place I felt I was never given in the banlieue. We thought there was a need for a place for young people to meet, to feel at ease, see friends, see family, stay a while.”

At the start they couldn’t afford advertising and relied on social media. O’Tacos has the biggest social media presence of any fast-food chain in France.

Other French taco joints are now vying for the market, from Tacos Avenue to the rapper Mokobé’s TacoShake. Concerned magazine nutritionists advise on how to reduce the huge calorie count (avoid the fizzy drink).

“It’s very much a French invention,” said Bernard Boutboul, of the food industry consultants Gira Conseil. He said the tacos’ high volume of food for €5 was a key factor in France, where McDonald’s prices are among the highest in the world. “Young people often say that after a Big Mac they’re hungry again at 4pm. After a taco, you wouldn’t be.”

Majd Hasnaoui, a former Paris nightclub events manager who opened four O’Tacos franchises in the Paris area in 18 months, said: “The kind of infatuation people have for O’Tacos – I haven’t seen that for a long time in fast food.”

Martha, a 16-year-old high school student, was finishing lunch. “I like the cheese sauce – you don’t get that anywhere else,” she said. Her mother wasn’t keen on the high calorie count, but she still went at least once a fortnight. “It’s where you see your friends.”