Green’s Dictionary of Slang

(US) average, run-of-the-mill, unexciting, basic.

1968		New Scientist 15 Aug. 351: This is the kind of ‘meat and potatoes’ information amateur astronomers [...] are eager to glean from an experienced observer.
1983		J. Ciardi A Second Browser’s Dict. 182: Meat-and-potatoes. Basic. [...] Let’s get down to the meat-and-potatoes.
2000		G. Pelecanos Shame the Devil 117: Wants to keep this a meat-and-potatoes, middle-of-the-road, bar-food kind of place. I’d like to do a whole lot more.
2007		C. Goffard Snitch Jacket 175: It’s [i.e. a pistol] blue-collar, meat-and-potatoes, just like you said.