i can offer info here!
the best, and i mean best, hot dog and hamburger joint i have ever eaten at is down the street. they prepare them completely, and before serving wrap them in foil. they sit like that for a few minutes before you get them. i do this now at home and it really, really, really, "bakes" in all the flavors and makes a better sammich. this may be exactly what you are remembering.
either way, try it, you'll like it! it's not for every sammich though...
-In memory of a friend.
avatar by grillman. patent pending.