In Boston there was a shack on Charles Circle just outside Mass General Hospital known as Buzzy's Fabulous Raost Beef. It was one of the few 24 hour joints in Boston. The Number 1 Combo was Rare Roast Beef, BBQ Sauce and Cheese on a Soft Onion Bulky roll with Frites and Onion Rings. While I know there is a lot of working class food here in LA, I haven't heard of anything similar to this and I hope I'm wrong.
The postscript: Buzzy's met the wrecking ball in 2002 when Mass General was expanding their cancer unit and building a hotel.