Katz's Deli (205 E Houston Street, NY)
I really have a love affair with Katz's Deli. We ate here 3 out of the 4 days while in NY, always making room for the delicious Pastrami Rueben. Make sure you always tip the guy slicing your pastrami (ensures a larger sandwich, not that it isn't already large enough!) and ask for it to be juicy, to avoid getting a lean cut. A classic NY institution and never to be missed while in NY.