When an American blogger named Tieghan Gerard naively dubbed her quick noodle soup recipe “chicken pho”, it caused a storm in a soup bowl. She was accused of whitewashing the iconic Vietnamese dish and misappropriating a culture and its people. Although the creator of Half Baked Harvest with millions of followers apologised and renamed her recipe “sesame chicken and noodles in spicy broth”, many Vietnamese Americans believe the title change was not sufficient and that the issue extends far beyond food, especially with the current rise in hate crimes targeting Asian Americans.

You think you know pho, but you really don’t because pho changes

While the culinary catastrophe played out on Instagram and had everyone from chefs to influencers to food lovers up in arms, the upside was that it shone a fresh light on Vietnam’s beloved national dish and its long history both in Vietnam and across the world.

Pho, a fragrant, nourishing and gently spiced beef and rice noodle soup, is relatively new in the Vietnamese culinary canon – only appearing in written records in the early 20th Century – but the history of this humble soup is both as subtle and complex as its flavour.

“I have had pho for all my life, but the story of pho is very rich,” said Andrea Nguyen, acclaimed Vietnamese American cookbook writer and James Beard winner. “And so, you think you know pho, but you really don’t because pho changes.”

While most historians agree that pho was invented in the late 19th and early 20th Century in northern Vietnam during French colonial times, its origins are murky. Some believe pho was an adaptation of the French one-pot beef and vegetable stew pot-au-feu, which shares a phonetic similarity to “phở”. Others say it was from the Chinese communities who settled in the north of Vietnam and sold a dish called 牛肉粉 (beef with noodles). The Chinese character for 粉 is pronounced “fuh”, which is similar to the Vietnamese “phở”.

Alex Tran, a Vietnamese chef and food writer who is currently based in New Zealand, suggests the origin of pho may be a combination of both. “Rice noodles and other spices used in making the broth undoubtedly have a connection with Chinese people in the north. However, beef is not the daily meat of the Vietnamese as we use buffaloes for farming. Only under the French colonial regime did the consumption of beef start to appear and bloom.”

Whatever pho’s origins, it is both beloved across the country as its national dish and a matter of fierce local pride and contention, where each region has its own preferred take on the ingredients.

“I personally would call it a dish that unites and tears us apart,” Tran said. “This is our national pride, but we would never settle on which type of pho is the ‘real pho’. If you want to make Vietnamese fight each other, ask them which pho is the best.”

While many overseas pho connoisseurs will be familiar with Saigon’s southern-style of pho, which has a sweeter broth and a liberal use of garnishes and condiments, the first version of the soup is thought to have originated in the north, 100km south of the Vietnamese capital of Hanoi, in Nam Dinh province.

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Here, south of the rich, fertile Red River Delta, a wide flat horizon embraces rice paddies, banana trees and bamboo hedges. This agricultural region, where most of the workforce were traditionally farmers, is also where most of the best-known pho masters in Vietnam come from. Many of them are linked to the Co family in Van Cu village, south of Nam Dinh city.

The peaceful village is surrounded by traditional green rice paddies that contrast with the red tile house roofs. At the village entrance is a shop with a pho sign that has hung there for many generations. This is the hometown of Vu Ngoc Vuong and his uncle Co Viet Hung, who at 87 is one of the oldest pho masters alive. Vu Ngoc Vuong is an award-winning pho master himself, with a chain of five pho restaurants plus a rice noodle workshop in Hanoi.

According to Vuong, when not cultivating rice, his ancestors travelled to towns and cities where they worked as street vendors. They made and sold bánh đa cua, a type of river crab soup using the tiny crabs that were abundant in the rice fields to make a seafood broth that’s served with a type of white flat rice noodles, similar to pho noodles. They also ate a traditional soup unique to the region called xáo, which was made with slices of water buffalo meat cooked in a simple bone broth with rice vermicelli noodles, spring onions and herbs.

Although no one is sure exactly how pho came about, most believe that villagers saw an opportunity in in 1898 when French colonialists started constructing the Nam Dinh textile plant. French technicians and thousands of workers flooded into the region to work on Indochina’s largest silk plant, and these two soup dishes were likely combined and modified to cater to French tastes.

“The French like beef so the villagers tweaked it by adding beef to the bánh đa cua,” Vuong said. “Also, they were given the discarded bones by the French who came to build the textile plant, so they took them back and boiled those to make the broth. They told us that was how pho was created.”

As construction workers moved from Nam Dinh to Hanoi to work on the Long Bien bridge project, the nourishing noodle soup quickly spread beyond the village. Carrying portable pho stalls on poles over their shoulders, impoverished villagers followed the construction workers, making a good income from selling pho, and the meal-in-a-bowl soon became a favourite for people living in the capital.

“The first person from the Co family who brought pho to Hanoi was Co Huu Vong. If he was still alive, he would be 130 or 140 years old,” Vuong said. “He came to Hanoi and rented a house. Young men from the village came and made pho; they took their mobile stalls around Hanoi during the day and went back to the house to sleep at night.”

Co Huu Vong’s sons and daughters eventually set up pho shops in Hanoi’s Old Quarter, and a few of those, now run by the third generation, are among the highest regarded pho vendors in the city, such as Phở Gia Truyền Bát Đàn and Phở Bò Việt Hoà Cụ Chiêu. “Ninety percent of my village have moved to Hanoi to live and run pho businesses, only 10% have stayed in Nam Dinh,” Vuong said.

From here, pho went in very different directions. In Nam Dinh’s version, beef slices are wok-fried with garlic, greens and a piece of tomato, then placed on top of blanched noodles before pouring a huge ladle of the aromatic broth into the bowl. Meanwhile, Hanoians took a far minimalist approach to the dish.

In Hanoi, pho is all about the quality of the broth, with some feeling that even herbs can distract from the flavour. According to Mrs Bui Thi Suong, a cultural ambassador for Vietnamese cuisine, beef pho broth in Hanoi is made of just beef bones and beef meat; while chicken pho broth only has chicken. Heading further south you don’t see that same specificity. Bun Bo Hue broth in Hue in central Vietnam, for example, uses both beef and pork plus more complex seasonings.

“The single use of an animal type in broth is very similar to the French cooking, which makes the taste more delicate and refined,” Suong said. Today, many purists say that the most “authentic” pho is from Hanoi.

Vuong believes that the broth is the litmus test of a good pho. He explained that a good broth should have a deep and sweet flavour from the marrow bones that have been simmering for hours, yet it needs to be clear, amber-like colour and subtly spiced. “Spices used in pho should be subtle undertones of flavour rather than complex layers. When the customers taste it, they shouldn’t feel any spice stronger than others,” he said.

Although beef pho was the go-to in Hanoi up until the mid-20th Century, the dish continued evolving. In 1939, the government tried to curb the slaughtering of cows by forbidding the sale of beef on Mondays and Fridays, and Hanoians had to reinvent pho to satisfy their cravings. Chicken pho was embraced by residents of the capital, and today, along with beef, it remains a much-loved version in Vietnam and beyond.

Today, many purists say that the most “authentic” pho is from Hanoi

Nguyen says her fondest moment eating pho in Hanoi was “a spectacular chicken pho”. “By that, I mean it tasted just like my mother’s pho, yet it had all of the chicken parts that I have never eaten before,” she said. “The chicken broth was so beautifully made, and it tasted like tonic. It’s like a wonderful medicine.”

In 1954, as the French colonial period ended and Vietnam divided into two, millions of northern Vietnamese migrated towards the south. Pho came with the migrants to the new lands and was adapted to the local taste, culture and produce of each region. The flavours of pho could be sweeter, saltier or spicier depending on the degree of local preference. What remained consistent was the clear bone broth, the soft white rice noodles, the tender meat slices and green spring onion. The garnish, condiments and additions are where things diverged. In Hoi An, on Vietnam’s south-central coast, for example, pho is served with crushed peanuts, a local chilli oil called ớt rim, pickled green papaya, Thai basil, fresh chilli, lime and fried baguette slices on the side.

Saigon’s cultural diversity, with its large Chinese and Cambodian communities and the availability of new ingredients, further fuelled the dish’s evolution. Rock sugar from Chinese cooking, and white radish, an ingredient of Cambodian noodle soup kuy teav, were added to the broth to balance the saltiness and make it sweeter. “The flavour of Saigon pho tends to be more sweet than savoury, whereas Hanoi is more savoury than sweet. And the other thing about Saigon and southern style foods is that everything is larger. So the bowls of pho are far bigger,” said Nguyen.

And while Hanoians only traditionally used mint from the capital’s Láng area, in Saigon, condiments like fermented bean and chilli sauce and garnishes such as bean sprouts, basil, cilantro and rice-paddy herb were placed at the table so diners could customise the soup to their preference.

“Southern people are very easy going,” said Suong. “They don’t mind a bit of change in the use of seasoning. It is actually refreshing for them.”

After the Vietnam War ended in spring 1975, many people from the south, mostly Saigon, fled to the US and other parts of the world, taking southern-style pho with them. Pho has taken root wherever the Vietnamese are and has now become the most recognised Vietnamese dish around the world.

Nguyen observes that as Vietnamese food becomes more popular, people outside Vietnam are starting to be educated on its many variations and permutations, just as regional Chinese cooking – from Shandong to Sichuan – has becoming increasingly trendy in recent years. “It changes from what was brought over here initially by Vietnamese refugees, and becomes perhaps closer to the experience that you would get in Vietnam,” she said.

Changes are happening in Vietnam, too. Imported beef and pho chains run by expatriate Vietnamese are redefining the pho landscape in Vietnam. “So you know it goes back and forth, the direction is very fluid,” Nguyen added.

Pho by nature is a versatile and easily adaptable dish. But as pho keeps evolving, the concern – as seen in the outrage over Gerard’s dish – is it might lose its soul in the process.

“I think that what’s important is for people to understand the origins of pho. And for people to be really creative with it, they need to understand where pho came from and appreciate the people who make it,” said Nguyen.

Suong agrees that recipes aren’t stagnant and thinks that no one could cook pho exactly like it was 100 years ago. “The traditional and the modern need to be in parallel so pho can evolve,” she said. “[But] we need to protect the origin of pho so we know our roots.”

Culinary Roots is a series from BBC Travel connecting to the rare and local foods woven into a place’s heritage.

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