Bo d B is must when traveling through down-town. This hole-in-the-wall serves up great sandwiches and whole plates at extremely reasonable prices. And everyone knows, so sometimes you'll have to queue up with the rest of the crowd.
Fresh-made sandwiches with a choice of salads and dressings, as well as whole diner plates for very cheap, makes this a great and healthy budget option downtown. You probably won't escape the tourists, but at least your money's not going into a corporate sink-hole. And the music's usually decent.
Try the bravas here - they're well-made and come with four different dipping sauces.