This year's must-eat: 'bánh mì'

Can a sandwich be fashionable? According to savvy foodies, the only snack to be seen with is a Vietnamese roll called a 'bánh mì'. Tim Walker tries a tasty trend

Scoff if you will – in fact, I recommend it – but there's such a thing as a fashionable sandwich.

Like a lot of street trends, this one has been appropriated from the developing world, popularised by urbane New Yorkers, and is now finally reaching our shores. The bánh mì (pronounced "bun mee") may look like a posh bacon roll, but encapsulated in this apparently simple snack are all the historical flavours of Vietnam.

A light baguette, smeared with homemade mayonnaise and pork liver pâté, then packed with an array of Vietnamese ingredients, it's the year's must-eat sandwich. "When burritos and Mexican street food were popular a couple of years ago," says chef and food blogger William Leigh, "I thought, bánh mì will be the next big thing." And it looks like he may have been right.

For some time, the only place in London to serve this delicious south-east Asian snack was the Loong Kee Café on Kingsland Road in Shoreditch. But in the past few months a number of the capital's establishments have added it to their menus: Viet Baguette in Fitzrovia; Banzi in Surrey Quays; Café Bay in Denmark Hill; and the Banhmi11 and Baguette+More stalls in Broadway Market and Greenwich respectively.

I get my first taste of this elusive sandwich, however, at the Sunday Upmarket off Brick Lane in Spitalfields. The Món Me (pronounced "mon mare") market stall is run by Mylo and Hanna, two Australian friends of Vietnamese parentage, who now work in London as a lawyer and an accountant. Their real passion is for the food their mothers used to cook them at home in Sydney. Hence the name of their street-food business, Món Me: "mum's dish".

The ingredients of bánh mì vary from region to region within Vietnam, says Mylo, but they all have common elements: the baguette, traditionally made with rice flour to ensure that it's light and crispy; the butter or mayonnaise; the pâté; the fresh salad of pickled carrots and daikon (white radish); thin slices of cucumber; coriander and chilli; and crucially, a hefty handful of slow-cooked pork. The Món Me "special meat baguette"– my choice – also contains homemade pork sausage, barbecued meatballs and, naturally, a sauce made from a secret family recipe.

My first bite is a revelation. Far from being overwhelmed by the bread, the delicate Asian flavours are all perfectly differentiated, with a thrilling chilli kick. No unseemly juices run down over my hands, nor is there any excess filling left at the bottom of the paper bag afterwards. In fact, there's just enough of everything to fill me up without weighing me down with wheat or meat.

Forget burritos. The bánh mì is a sandwich for the ages. "It shouldn't work, but it does," says Leigh, whose blog The Boy Done Food betrays his infatuation with Asian cuisine."I think it's the combination of sweet, salt and sour. It's a bizarre mix that absolutely works. You've got all these competing flavours that come together and work really well in unison," he says.

"If you're making bánh mì ingredients yourself, be warned that daikon, when you pickle it, is really smelly and pungent ... But actually, it tastes fabulous."

Bánh mì has its origins in the French occupation of Indochina from the mid-19th to the mid-20th century. "Like all oriental countries," explains Mylo, "Vietnam's staple dish is rice. But when the country was colonised by the French, it was introduced to bread and pâté. Vietnamese culture revolves around food, so they took that palate and added Vietnamese elements to it: pickles were common because it's a poor country and uses a lot of food preservation processes; the Vietnamese also eat a lot of pork, which is the filling for the original bánh mì."

These days, the bánh mì is a more versatile beast. As well as the many pork-based varieties, there are versions featuring scrambled eggs (bánh mì trúng), chicken (bánh mì ga), or tofu (bánh mì chay). Many American cities have their own signature varieties of bánh mì, but the US is not the only Western country with an established fan base for Vietnamese street food.

Bánh mì shops have popped up in Australia, Canada, Russia, the Czech Republic, Germany, Poland and France. Mylo and Hanna, when they first arrived in London from Sydney around four years ago, had to take weekend trips to Paris to get their bánh mì fix.

"As kids at home we would pick them up on the way to school, or our mums would prepare them for us," says Mylo. "Our mums are from the last generation of Vietnamese women who cook home-style slow-cooked food, because they were the last generation who grew up in Vietnam before moving to the West. They still know the traditional recipes and they taught them to us.

"When we came to London, we found that there was heaps of Vietnamese food, but it was all very similar and not as traditional as we would have at home. We started making bánh mì, spicy noodles and other things for our friends and they encouraged us to do something with it. We wanted to sell bánh mì first because it just wasn't available in London, but now we're hoping to add our menu and introduce Londoners to more of our mums' cooking."

Their stall may only be open on Sundays for now, but Mylo and Hanna spend half of their week preparing the ingredients. Making their own mayonnaise and pâté is the easy part. The pork belly is marinaded on Thursday and takes three days to cook, using a secret process (devised with the help of Mylo's brother, a trained chef who used to cook at Claridges) to get the texture and proportions of fat and skin just right. The chicken takes six hours to roast. The pork sausage is homemade, wrapped in banana leaf and steamed to achieve a specific, fresh-vegetable scent. "At the end of the day," says Mylo, "it's just a sandwich." Yes, but what a sandwich.

Món me's Banh Mi in London