My favorite meal is made out of leftovers.The family is from South Dakota and is German so we do it a little different. We use rice instead of potatoes.
I make a roast beef in the oven. Sunday dinner. Mashed potatoes gravy, dinner rolls etc.
Save the leftover beef and the gravy,
The next day slice your beef into 1/4" thick slices. Toss them into the leftover gravy. If there's not enough stretch it with some store bought (eek).
Cook that gravy and beef slices covered on the stove top low and slow for about two hours until its almost falling apart. If you have a glass covered pyrex dish and want to use the oven, that works too.
Cook some rice.
Serve on diagonally sliced toast with a pile of rice in the center. Then dump on the gravy...lots of gravy.
If it's done right you can cut it with a fork.