Stir fry is a great way to use little bits of this and that and leftovers work very well for it. It's also fairly easy so even a beginner can cook a thrifty and healthy dish.
And don't be stuck on the idea that stir fry has to be Asian!
One of the best dishes I create is a Mexican stir fry. I use a little leftover wild rice, taco or enchilada seasoning, bits of meat, a few vegetables like baby corn, onion, peppers, and even broccoli, and a splash of olive oil. It all combines to make a lovely dish with Southwestern flair.
For the meat, leftover meat loaf broken into small bits is good, as is leftover beef roast, chicken, or even fish! Don't forget that you can top each serving with a little cheese or shredded vegetables, too.
Let your imagination run wild and try stir fry with whatever you have on hand, cooked or raw. You might create a family favorite while making use of food that's been lingering in the fridge a bit.
If you like stir fry or haven't tried making it but would like to, check out this free cookbook . The minestrone recipe sounds particularly tasty to me and certainly unusual.