You mean for a sit down lunch or take out? There are tons of good places within a short walk into Soho or the West Village...
Grandaisy (maybe, those sandwiches are kinda small)
Banh Mi Saigon Bakery
Once Upon a Tart
Blue Ribbon Market
Despana (a bit further of a walk)
Murray's Cheeses takeout section
Aroma (coffee shop)
Also checkout the ladies who write lunchstudio.blogspot.com since they go out for lunch frequently and are always looking for places near their Soho studio.