Roast beef was a food dish originating from Earth, consisting of a cut of cattle meat (beef) roasted in an oven. It was either served hot, or cut into thin slices and served cold, usually in sandwiches.
Field ration packs of roast beef and blueberry pie were provided to the Starfleet Corps of Engineers team rebuilding the cultural observation post on Coroticus III in 2376. These were the last variety of rations left four days into the mission, and Fabian Stevens considered starvation preferable to eating them. (SCE eBook: Fables of the Prime Directive)