I work in midtown right on top of the BDFM station at 42nd Street. I know my way around 34th to 50th streets between 7th and 3rd avenues for lunch, but I realize it's silly that I don't use the subway more to go further uptown or downtown.
Every so often I'll remember that I need a slice from Joe's on Carmine and will hop on the train and be able to get down there, eat, and get back to work in 30-40 minutes. I can take my full hour lunch most of the time, so I know I can get as far down as Grand St. on the BD or Delancy/Essex on the FM, though I don't think I'd go much further uptown than Columbus Circle or the 63rd St F.
What are your favorite, realtively quick and under $10 lunches within a block or 2 of stations below 34th street or above Roc Center?