Chinese roast pork on garlic bread is one of the great New York sandwiches, a taste of the highest peaks of Catskills cuisine: thin-sliced, Cantonese-style char siu married to Italian-American garlic bread beneath a veil of sweet-sticky duck sauce. Sandwich historians suggest that it was the creation of Herbie’s Restaurant in Loch Sheldrake in the 1950s, and it soon became a favorite of the summertime borscht-belt crowd — after-show entertainers and Jewish bungalow kids with observant parents lining up alongside one another for this taste of illicit exoticism, unkosher and delicious in the extreme. ‘‘It’s the ultimate assimilation crossover food,’’ the food writer, radio host and erstwhile restaurant critic Arthur Schwartz told me. ‘‘That sandwich is a symbol of acculturation.’’