Recognizing this may be difficult to define, it’s something that’s long puzzled me. Often, I’ll see people post about a restaurant, or a recipe, and either vouch for the authenticity or rail against its inauthenticity.
So I’m curious: how do you define “authentic” - and is it important to you?
Ohboy… 
Usually means the way the speaker’s mom /grandma / auntie made it. I usually say “traditional” instead.
Though there are things that are straight-up inauthentic, like cream in carbonara. Make that if you like it, but don’t call it carbonara.
Or call it “carbonara with additions of…” which I do periodically.
I think of “authentic” with things like “sweet and sour whatever”.
All recipes are different. Like music. All of it came from somewhere before. Authentic probably not. Original yes.
How about “likely to be made/served/found the same way in its region/country of origin”? Not sure about changes that occur when peolle move from the place of origin. If it’s not found that way where it began it’s a “non-traditional” interpretation?
I asked my students this question on the first day of our food studies class 
For me, authenticity is subjective, contextual, and variable. Folks are often extremely passionate about what is/isn’t authentic, defined by their own experiences, ideas, family and cultural history, and through others - especially those considered “experts” - definitions.
That’s exactly why I avoid it. Not a very useful word.
Since sweet & sour (something) was mentioned earlier, we can go into the history of it for a better understanding (and to cement the fact that yes, authenticity is somewhat a capture of a moment in time as food evolves, to better understand the frame of reference). Yes, sweet and sour is not Chinese American, faux Chinese. There are non traditional (re: shortcut driven) versions for sure.
Back in the old days, fatty pork was cheap and lean pork was expensive. In order to make fatty pork (e.g. belly) easier to eat, Cantonese Chinese came up with the idea of starch coating pork cut a certain way, deep frying, drain the oil, then cooking a separate mixture of a sauce that is sweet and sour, then cooking both together with carefully controlled wok temperatures and searing. This made the pork less filling but enough acidity and some sweetness to stimulate appetite.
As the economy improved over time, people became more health conscious, and nowadays even the most traditional of Cantonese restaurants, sweet and sour pork cuts of meat were shoulder cuts (similar to that used for Cantonese char siu). The sweet and sour sauce flavors would come from a mixture of pineapple, ketchup, vinegar at the absolute bare minimum. The old school traditional places would make the sweet and sour more complex and nuanced, by also adding fresh and dried hawthorns, perhaps a sour plum (think Japanese umeboshi but different), and adding some sugar for adjustment. The fastidious places may switch it out depending on the season, replacing pineapple when not in season with pickled ginger. There is one very well known restaurant in Hong Kong that uses three types of hawthorn for the sauce (fresh berry, dried sticks, and flakes - like the candy) and yet I believe goes back to pork belly. The criteria (by eaters) for a plate of sweet and sour pork would be the ideal amount of wok breath/wok hay, fried pork that is not greasy, but even with the sauce coating the exterior is crunchy and the interior almost fluffy like, with a delicate balance of sweet and sour flavors from the sauce as well as the textures from the other ingredients. There should be no excess sauce smothered all over the plate (e.g. the cornstarched thickened varieties you find in many places abroad), though it is ok if there is a very shallow pool of the sauce that sinks to the bottom. And finally even when eating halfway through, the dish is still very respectable and tasty.
Fast forward to today, there are maybe 15 restaurants that do what locals, food writers consider traditional sweet and sour pork (where a lot of work is put in) in Hong Kong, perhaps more if you include the neighborhood joints that do it decent, but not at the level of those 15 or so that would satisfy the extreme nitpicky and traditionalists. Plenty of other shortcut quick fix places of course.
Then you have the Chinese American renditions in various parts of the world (e.g. Chinatowns).
You have Korean Chinese variants (tang su yuk), and sugar vinegar spareribs which are completely different in Shanghainese cooking. And Japanese Chinese su-buta where the taste is less nuanced, but also can be delicious in its own right.
Oh by the way, the even more original Cantonese sweet and sour pork, was sweet and sour spareribs apparently. Meat and fat around the bones. Think pork spareribs black bean sauce dim sum variety, but cut into bigger pieces. Pork/pork belly was substituted without bones, to make it easier for Westerners.
All of this information was compiled from various Hong Kong media / print sources (all credible), and one archived academic university research paper (also from Hong Kong).
So of all versions listed above that originated in Hong Kong and if we were to include overseas versions, which versions are authentic? Assuming the informational sources are authentic as well?
looks like someone watched Ugly Delicious over the weekend
Not a fan of David Chang, though I may watch that someday. I don’t need his show for information and knowledge on Asian food (except maybe for his own stuff which I’m clueless about) 
Ugly Delicious has a lot of interesting people and food. I found it very entertaining.
I’ve heard great things about the show from people who aren’t fans of Chang, so yes eventually I will watch it.
So going back, maybe the right words to use aren’t “authentic” or so much as “traditional” (though a better usage of the two). Perhaps we should start using “Hella Good”, “Da Shit”, “Old Skool” or “Legit” which has looser interpretations and can be used in jest at the same time.
Though it is important to know why something is done the way it is, assuming it is a stabilized version of an evolved dish that has a longer history, and is considered to be the best snapshot in time, and that is also regarded to be the most delicious by the utmost picky of gourmets and gourmands. If the why and reasons for doing a dish results in more complexity and nuance that a shortcut fails to achieve, and is worthy of the trouble (and cost to an extent) then I’m all for it and maybe a bit more justified in using “authentic” or “traditional” (all in subjective context). Though the gray area is if the elaborate steps involved are modern techniques resulting it being even tastier than the old / old school preparation that was more laborious (and I’m not talking about sous vide machines and modern kitchen toys). If it is done for the sake of making money, instant fame, ego boosting to overcompensate for insecurity, and cooked without any soul or passion (all too common everywhere), then it’s just a pile of wasted ingredients sloppily put together hoping customers don’t know better (faux authenticity / Fauxthenticity).
Authentic / traditional doesn’t always mean good. I’ve had some traditional rustic scamorzas in Italy that were so sharp they tasted more like vomit than cheese. Wine often used to be so bad that the taste could be improved by adding seawater.
Yes that’s very true and for sure. Assuming what they say is historically accurate, that evidence of grape wine was found circa several thousand BC in Greece, Armenia, and of all places China, doesn’t mean those taste good (or authentic) but it took other regions to iterate and improve upon it (who in their mind would want a replica of that style sub par table wine over First Growth Bordeaux or a Barolo Riserva, let alone small producer local table wine in Italy).
Dim sum… from a place where the focus was tea and a place for conversations by officials, businessmen, government type folks (the dim sum snack then being two gigantic buns with a pot of tea), and where brothels that also served alcohol co-existed as a separated entity, eventually merged to become places that served alcohol (eventually becoming high end seafood restaurants) and dim sum, while brothels were outlawed. And the giant buns became one of many other offerings, and eventually smaller sized buns (and smaller portions of bites) to add variety to the mix. Har Gow was a bit of a later addition, and the latest additions to the classic lineup (spareribs, chicken feet) were late 60s add on’s to the lineup. Everything else after that were the result of restaurants trying to be different (including the modern day fusion and a lot of confusion). The only way you can differentiate quality is the skill of the chef (and of course the resulting flavors, textures, balance). Then fast forward to the present in Hong Kong, high real estate costs, many old school places closing, and younger generation don’t want to apprentice under the masters (too much work, too much time) nor do they want to keep the tradition alive. So less effort goes into preservation (why do so much work that makes so little money). Some places might try to revive almost or actually extinct recipes, some come close, and surely there are places that are just doing it for the money to capitalize on sentimentality. And thus, who is to judge where does authenticity and tradition start and end in this spectrum?
“Authentic” is an oft-used line of crap. Not that it doesn’t have its time and place for proper usage, but take, for instance, “Mexican Food.” There’s very little in the USA that is really “authentic” yet a modestly decent amount of “good,” depending on location. Yet if you go to Mexico, there are countless thousands of mediocre restaurants, and you know what? Every one is “authentic.”
Make me good food, inspired by a homeland, with fresh local ingredients. I don’t care if you’re not from there - I’m not going to accuse you of appropriating anyone’s food, and all is good.