Another idea that I suspect – and hope – is on the way out is the insistence on “authenticity.”

You can tie yourself in knots trying to source the ingredients to make the most supposedly authentic version of a particular dish. Is the olive oil in your pesto Ligurian the right one? Does your paella contain the required snails? The truth, however, is that no recipe is ever truly authentic. A dish is always borrowed or tweaked from somewhere else, and that is no bad thing.

A couple of years ago, the Israeli chef Yotam Ottolenghi, who is famous for his inventive flavours, was vilified by readers on the Guardian website for publishing an online recipe for Irish stew. Mr. Ottolenghi made no pretense that his stew was anything anyone would recognise in Ireland, where the original stew is nothing but mutton, potatoes, onions and water. His version – an homage to his Irish husband – contained white wine and herbs and was finished with an aromatic paste of orange zest, garlic and parsley. He saw these addition as a way to adapt Irish stew to his own palate. But to the chef’s online critics, these tasty seasonings, especially the orange zest, were a violation of the holy memory of the original Irish stew.

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The cult of authenticity is based on the idea that recipes are suspended in time and place, like berries in an old-fashioned Jell-O mould. Yet since the discovery of fire, every generation of cooks has rewritten the rule book of cooking, depending on the ingredients and resources available and the tastes of the times. Modern apples tend to be sweeter than older varieties, so to make an apple pie that tastes authentically like one of the 1950s, you would need to use less sugar.

Even in Ireland, stew is evolving. I recently ate the best Irish stew of my life at a restaurant in Galway run by a brilliant chef from New Zealand named Jess Murphy. In place of potatoes, Ms. Murphy uses an assortment of local root vegetables and seasons the broth with lovage, an herb that tastes like celery, only earthier. Alongside the stew was a damp dark soda bread and superb Irish butter.

If her Irish customers were offended by her updated stew, they showed no sign of it. Sipping the delicious lovage-scented broth, it suddenly occurred to me that it’s more respectful to a dish to cook it and keep it alive than it is to insist on making it the exact same way it happened to be made a hundred years ago.

“Who cares if it’s authentic, so long as it tastes good?,” Mr. Ottolenghi remarked at London’s National Theatre in London in August, talking about the Irish stew affair. I was on stage with him and cookery writer Nigella Lawson, talking about “food and identity.” Both said that when it comes to food, authenticity is not as important as cooking something authentically delicious. Ms. Lawson said she believed it was important to respect the origins of a recipe and to acknowledge its roots but also to recognise that cooking traditions are always changing.

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It’s hard enough making time for cooking in the modern world without giving yourself the added burden of authenticity to live up to. A few months ago, the journalist Stephen S. Hall traveled to the city of Amatrice in the Lazio region of Italy for the New York Times, in search of the “real” pasta all’Amatriciana – the deliciously comforting sauce of tomatoes and cured pork. What he discovered was that he had been cooking his favourite pasta dish “wrong” for the past 40 years.

Following Marcella Hazan’s classic recipe, Mr. Hall had always made his Amatriciana with pancetta, butter and onions (a recipe that I can confirm is pure comfort), yet he found that in Amatrice, onions and butter were never added to the dish. The true Amatriciana, he found, contained only tomato sauce, pecorino and guanciale (salt-cured pork jowl), which has a sweeter taste than pancetta. Locals were horrified when he confessed to using pancetta in his Amatriciana.

Is using pancetta instead of guanciale really such a crime? The thing that gets missed by those who cling to the idea of authentic food is that when you change the context of the cooking, you change the meaning. In Amatrice, guanciale is used in pasta dishes because it is a normal, everyday item. Outside of Italy, as Marcella Hazan wrote, “pork jowl is hard to get,” and therefore it’s a reasonable choice – and true to the original spirit of the dish – to substitute something that’s easier to find.

I am not suggesting for a moment that we should pay no regard to the origin of dishes. A British chain, Marks and Spencer, recently caused offense by selling a vegan wrap sandwich that was labeled as biryani – biryani being a noble and festive Indian rice dish. This wasn’t so much an adaptation as an outright piece of misdescription.

But when it comes to authenticity there are bigger fish to fry than whether you used exactly the right variety of wine in your osso bucco. Our stores are full of items that claim to be something they are not. We are sold lemonade that contains no lemons and berry-flavour breakfast cereals that never saw a piece of fruit. A 2010-2012 report on seafood fraud by the nonprofit Oceana found that much of the fish for sale in the US was mislabeled. The group found, for instance, that 87% of the “snapper’’ on sale was mislabeled (it was mostly tilapia).

Rather than devoting so much of our energy and attention to searching for the authentic, we could ask a simpler question of our food. Is it real?