The Big Apple is the No. 1 food destination in the US, according to a perplexing new survey from SIXT, a premium car-service provider based in Germany. But New York City ranked a middling No. 7 in the world, behind Tokyo, Paris, Osaka, Porto, London and Seoul. Can we really be a lesser food town than Porto? The Portuguese city has one-fifth our population and is best known for its Francesinha sandwich of sausage, ham, and melted cheese in spicy tomato-and-beer sauce? It seems everybody wants to