If you can't consider Chillies local for Asian food then we can't consider tomatoes authentic Italian food either, but then at that point what exactly are you even talking about?
0: https://scholarblogs.emory.edu/noodles/2018/07/03/history-of...
I would wager that 300+ years is more than enough for any custom to be qualified as traditional.
> Austrian: America doesn’t have a culture — it’s only really been around for a few hundred years: my family has chairs older than that! We date back to the 1100s!
> (Best friend from China): my village’s local temple (the core) was more than 500 years old in the 1100s; your culture is still getting started!
> (Friend from Tyre): my house is in the new part of the city built by Alexander in 330 … BC. The old city was established further back in the past from the new city, than the new city is from now. Until your people have lived in a place for at least 2000 years, how can you really say you “own” it?
Then we got a beer & watched “Dancing With the Stars”.
As a consequence their culture is converging somewhat towards the cultural revolution which is only about 70 years old. So they are a young political culture in that regards, and politics dominates due to its military force.
For the record, I'm a Finn. By my own definition, there are maybe only three traditional Finnish foods that have survived that long. Carelian stew, särä, and maybe robber's roast (clay-pit mutton).
Whereas something like wine leaf rolls from Greece, Turkey and Lebanon - now those can be properly traditional.
The idea that before some certain point a culture was "frozen" is usually ahistorical. Certainly true for cultures of the Italian penninsula, on the Mediteranean providing easy access to wide swaths of land and peoples, part of a former empire that spanned continents.
Easy: as soon as the people who adopted it into the current form are dead and the adoption forgotten.
My grandmother's cherry island cake was almost certainly copied off the back of a package sometime in the 1920s or 30s; maybe it's an adaptation of a German or Hungarian recipe. Now it's a tradition in my family.