Aficionados of Chinese, or for that matter, any cuisine obsess over the authenticity of a dish, as if this aspect was a guarantee of its gustatory delight.  Authenticity is revered as an inherent and immutable property of a dish. Yet.just as any language is not pure or fixed, but forever changing, such is true for food. 
      The studies of Chinese food in America by historian Haiming Liu provide an excellent illustration of what he calls 'flexible authenticity.' He notes that in the 1970s,   significant changes occurred in the Chinese food served in Chinese restaurants in America.  The large new influx of Chinese from Taiwan made possible by the 1965 immigration law led to the introduction of dishes from many differenti provinces, Hunan, Sichuan,and Shanghai, which displaced the then long dominant Cantonese-based cuisine in Chinese American restaurants.
      However, Liu points out that these cuisines that the Taiwanese immigrants brought to America could hardly be considered 'authentic' because they relied on 'collective memory' of what these cuisines were like in mainland China before Chiang Kai-Shek's defeated regime  was driven by the Communist China in 1949 to flee to Taiwan, then called Formosa. In short, chefs tried to recreate these dishes, but often had to improvise and reinvent to achieve their goal.     Thus, what they brought to America in the 1970s was not "authentic" in the sense that they were the dishes served in pre-1949 mainland China.  (But, for all we know they might, in some instances, taste as well as or better than the original versions.)   Haiming Liu's 2011 paper in Chinese America History & Perspectives on the successful Din Tai Fung
restaurant chain from Taiwan iprovides a detailed case history that uses Shanghai dumplings to illustrate "flexible authenticity" of ethnic cuisines.