Authentic means the ‘real’ deal, such as authentic food. It’s deeply tied to culture, so the more one knows of the culture, the more one knows of the food. Vice-versa too. People immigrate to new countries, but need a way to preserve their culture. One way they do it is by having the same type of food that they had back home.
That would explain why San Francisco, with alot of Chinese people, has a big Chinatown and Chinese immigrants still cook Chinese food. Food is something you can take with you across to a new country. Landmarks and statues back home stay there. Language is attempted to be preserved too, like by teaching kids language-ie. Mandarin or Korean. Food is something relatively easy to pass among generations. So even a third, fourth-generation Asian-American could still connect with their culture through their home food.