South-east Asian cuisine used to mean chicken with an irradiated glow and bomb-sized clumps of egg-fried rice. In other words, sweet, heavily sauced Chinese food, brought to Britain by Hong Kong immigrants in the early Sixties that was tinkered with to suit our tastes and has since become part of our urban culture.
Then came more culinary diasporas: Thai, Japanese, Korean, Laotian, Szechuan Chinese and Vietnamese food. Vietnamese now has one of the most celebrated identities in the capital, thanks to "Little Hanoi", a stretch of east London's Kingsland Road, where restaurants like Quet Viet (formerly Au Lac), Loong Kee Café and Song Que compete to serve customers pho, Vietnam's legendarily important rice-noodle soup, and banh mi – a light baguette smeared with homemade mayonnaise and pork-liver pâté.
This latter dish landed in east London from the street-stalls of Vietnam via hip young New Yorkers, who have made it their sandwich of choice.
It's therefore somewhat unexpected to find that the latest evolutionary waypoint for British-Asian cuisine is a restaurant chain run by two English former marketing executives.
Husband and wife team Juliette and Stephen Wall took sabbaticals from their careers in 2004 to go travelling. In Vietnam they fell in love with the nation's street food and decided to bring it back to the UK – with their own twist.
A research trip to the Vietnamese restaurants of Chinatown in Los Angeles drew them to pho restaurants – places that specialise in a small number of dishes that revolve around noodle soup, as opposed to the hundreds of dishes you might find on your average menu along Kingsland Road. The duo wanted to keep it cheap and target the lunchtime market, and opened Pho, their first restaurant, on St John's Street in Clerkenwell, about half a mile to the west, in 2005. Capitalising on the close-knit community of architects and media professionals there, the brand was able to expand into outposts on Great Titchfield Street and then in Shepherd's Bush's Westfield shopping centre. The duo is now renovating a space for a fourth restaurant, in the plush South Lanes district of Brighton. They also hope to open a more high-profile location in Soho.
"Vietnamese food, unlike Chinese, Thai or Indian, is clean and simple and fresh," says Stephen. "When you go to Vietnam that's what really comes across. It's the abundance of fresh herbs; they give it this very distinctive flavour. It's healthy, and it's simple, and by focussing just on the soups we maintain that simplicity ethic.
"There's a temptation for people in this country to meddle with fusion cuisine. When our chef first came on board, he tried to put Chinese on the menu and that is something we resisted wholeheartedly," he adds.
What is also perhaps surprising is that something like this has not been done before.
The Wagamama chain, the brainchild of entrepreneur Alan Yau, began as a Japanese ramen restaurant in 1992 but has expanded its menu hugely – an excess inappropriate to the scale of the Pho operation. Then there are the more traditional Vietnamese restaurants, such as Hackney's Viet Grill (go there for sot tieu xanh, or baked duck with jalapeno pepper), which cater more for the evening market.
Pho has stolen a march on Pho 24, the most popular noodle chain in Vietnam, which has plans to roll out 30 branches across the UK, starting in London. The California-based Pho Hoa has meanwhile successfully cornered the pho market in the US.
Clearly, once offered the chance to enjoy Vietnamese cuisine in convenient and familiar surroundings, metropolitan Westerners can't get enough of it. According to fusion cuisine expert and chef Peter Gordon, whose new book Fusion: A Culinary Journey is published later this month, the appeal of Vietnamese food lies in its "refreshing, aromatic qualities" and its "unique spectrum of flavours", which differentiate it from other south-east Asian cuisine.
"I love all the fresh ingredients, the rice paper wraps, I find it really palate-cleansing," he says. "I like the lightness of touch; it's not as sweet as Thai food; there's a whole different aromatic spectrum". Unlike the Walls, Gordon believes that fusion cuisine is true to the history of south-east Asian cooking. "All the cooking from there comes from different parts of the world anyway," he says. "The chillies are from Mexico, coriander is a Mediterranean herb. Thai food is not pure, it has a lot of Muslim input. There's a lot of French influence from colonial times, especially in Vietnam."
To gain a greater understanding of Pho's cooking I was invited into the kitchen of their Great Titchfield Street operation to try to make a few of their summer rolls – a perfect example of the yin and yang (the marrying of "hot" and "cold" ingredients) intrinsic to Vietnamese cooking, and one of Pho's most important side dishes. I was introduced to Jit Pham, one of the company's long-term chefs, and attempted to emulate her movements with minimal cack- handedness: softening rice paper in water, allowing it to saturate, two springs of mint, sprinklings of lettuce, vermicelli noodles, coriander, carrot and mooli pickle, then rolling it as you would wrap a present in a bookstore production line.
The rolls are served with nuoc cham dipping sauce (a fish sauce mixed with lemon juice), and the sharpness of this complements the cooler taste of the herbs and vegetables in the roll. I saw the finishing touches being applied to a huge vat of chicken stock, before the addition of spices including roasted cinnamon, onion, coriander seed, fennel seed and cloves, among other spices. This and numerous batches of beef stock form the basis of pho, which can be garnished with spices and herbs (chillies, mint, Thai basil, sawtooth herb) according to the customer's preferences.
A summer roll and a bowl of pho might make your standard meal. "You can make it taste the way you want to," says Juliette. "You get your big bowl of soup, then the condiments, sauces and herbs and you put it all in. If you like spicy soup, you can make it the way you want it.
"In this country you get given your food and that's the way it is. In Wagamama they do noodle soups but there's not that much adaptability. We wanted to make something a bit more like Vietnamese street food, something which has something different to offer wherever you look."
Funnily enough, the Walls were in Bolivia when they decided to go with the Vietnamese idea. "Even six months after Vietnam, we were still raving about the prospect of doing something with Vietnamese cuisine," Stephen recalls.
On returning to the UK, Stephen became a full-time researcher on the restaurant project, while Juliette returned to her job. Stephen visited Los Angeles: "It allowed me to look at between 10 and 15 dishes and the idea of the restaurant fermented. The point was not to over-complicate it."
A successful trip to the bank manager later – "we owned a one-bedroom flat in Hackney, and it was on the line," says Stephen – it wasn't long before they found the St John's Street site, a former deli, and set about converting it with three friends. The space is canteen-like in design yet intimate, perfect for designers on the hop who fancy spending under a tenner on a lunch that's light and healthy.
"It's a cliché, but for the first two years we literally worked 15 hours a day, every day," concludes Stephen. "We might have taken the odd half-day off on a Sunday. Our life was that restaurant, our social life went out the window. If we saw our friends they came to the restaurant and had a meal there. We invested blood, sweat and tears." However, "It got easier when we opened our Great Titchfield store and we were able to put managers in place in Clerkenwell whom we could trust. Thankfully now, at long last, all that hard work seems to have paid off."
Make it at home: Vietnamese recipes
Ingredients: finely shredded lettuce, mint leaves, coriander or Vietnamese herbs, perilla (tia to), carrot and mooli pickle, cooked thin vermicelli rice noodles, 22cm rice papers, cooked tiger prawns sliced lengthways, cooked chicken, sliced. Serve with nuoc cham.
Wash your hands or wear clean gloves. Use a clean damp towel to roll on.
Dip rice paper in warm water to soften.
Place mint leaves in a line across the lower third of the rice paper.
Lay prawns across entire width of the rice paper, leaving sufficient at the end to fold in. Add in other ingredients, then roll it up, away from you.
Store chilled under damp, clean tea towel
Serve whole or sliced in two, with nuoc cham dipping sauce.
Pho Chicken Stock
Ingredients: chicken bones, cinnamon, star anise, black peppercorn, coriander seeds, cloves, lemongrass, ginger, white onion, red shallots, garlic bulbs
Bring water to the boil in a cooking pot. Wash the chicken bones.
Bash the lemongrass and cut the ginger in half, lengthways. Roast the ginger, garlic lemongrass and shallots in a dry, hot wok. Then add cinnamon, star anise, peppercorns and cloves. Add coriander seeds to the wok last.
Rinse any black flakey pieces off the onions and garlic. Add chicken to the boiling water, a few pieces at a time.Once all the chicken has been added, add the roasted spices to the pot.
It is important not to cover the pot when everything is added.
Bring bring back to the boil, and skim the foam from the surface. Oil can also be skimmed off as the stock cooks.
Reduce the temperature to its lowest when it reaches the boil, and begin to season.
Simmer for 2-3 hours, not longer.
Drain through the chinois and muslin cloth. Cool, cover and store in the fridge
Serve stock over blanched pho noodles and sliced cooked chicken. Garnish with sliced onion, spring onion and fried shallots. Serve with fresh herbs, beanshoots, slice red chillies and a wedge of lime.