Who owns a bowl of phở?

Few dishes inspire as much loyalty as phở. Ask a Hanoian about the bowls served in Ho Chi Minh City, with their plates of fresh herbs, bean sprouts and squeezy bottles of hoisin sauce, and you are likely to receive a pained look. Ask a Saigonese about northern phở, and you may be told, very politely, that it tastes of almost nothing. The argument can last longer than the meal. Behind the teasing, however, lies a question that has become a surprising bone of contention, at home and abroad: who, if anyone, gets to decide what a dish is?

Part of the difficulty is that phở's own origins are far from settled. Most food historians place its birth in northern Vietnam in the early twentieth century, somewhere around Nam Định and Hanoi, but they disagree about its ancestry. Some point to the French pot-au-feu, a beef stew whose final word may have given the soup its name; others stress Chinese influences, from rice noodles to the spices in the broth. The most likely answer is both, along with the simple fact that colonial Hanoi, with its French appetite for steak, suddenly had a surplus of beef bones. Phở was a fusion dish long before the word became fashionable.

Its later history is a story of movement. When the country was divided in 1954, hundreds of thousands of northerners moved south, bringing the soup with them, and southern cooks in turn adapted it to local tastes and a more generous supply of herbs. After 1975, refugees carried it further still, to California, Texas, Paris and Melbourne, where it eventually crossed over from community restaurants to mainstream menus. Each move added something and, purists would argue, took something away. Today it is sold in airports, supermarkets and instant-noodle cups, sometimes in forms its inventors would barely recognise.

It is precisely this success that has made questions of ownership so fraught. A few years ago, an American food magazine published a video in which a non-Vietnamese chef explained the 'right' way to eat phở, advising viewers to skip the sauces; it provoked a storm of criticism. The objection was not that outsiders had no business cooking the soup, but that they presumed to teach it back to the people who had made it, while the cooks who had built its reputation remained largely invisible. Meanwhile, in Vietnam itself, local authorities have begun seeking official heritage status for regional versions, hoping to turn pride into tourism.

Both impulses are understandable, and both carry risks. Recognising the people behind a dish is a matter of basic fairness, particularly when their cooking was once dismissed as cheap or foreign. Yet treating a recipe as property, to be guarded and certified, sits uneasily with the way food has always evolved. Had the cooks of 1950s Saigon deferred to northern tradition, there would be no herbs on the table today; had the first sellers in Hanoi refused to borrow from French and Chinese kitchens, there would be no phở at all. Food that is not allowed to change is food that is slowly dying.

A more useful distinction, perhaps, is between authenticity and acknowledgement. No version of a dish can claim to be the authentic one, since every version is a snapshot of a tradition in motion. What cooks and eaters can reasonably be asked for is acknowledgement: knowing where something comes from, giving credit where it is due, and resisting the urge to tell others how they ought to enjoy their own food. By that standard, the endless bickering between Hanoi and Saigon is not a threat to phở but a sign of its health. Dishes that nobody argues about are usually dishes that nobody cares about.