Interesting NY Times piece on underground restaurants:
Restaurants of dubious legality, where food is cooked in apartments and backyards, abound across the United States. These underground restaurants range from upscale to gritty, and are born from youthful idealism, ethnic tradition or economic necessity. They lack certification from any government agency and are, strictly speaking, against the law. You dine in them at your own risk. If you can find them.
Read the whole thing here.