You could make a beef hash- this also works for leftover roast.
Preheat the oven to 350 degrees.
In a dutch oven or a pot with a lid, sautee some onions in a little butter or olive oil. It is really good if the onion get thoroughly cooked. This will allow a bit of crustiness from the onions adding to the thickening of the "gravy". Remove from the stove.
Wash and quarter about 6-8 red potatoes or 6-8 Yukon gold potatoes. Put in the potatoes and the cubed leftover steak in the pot along with the onions.
Add about half of the box of a 32 oz. beef broth box. If cheaper you can buy 2 cans, but the box allows for you to store in the refrigerator any leftover broth. Depending upon how much meat you have you might have you might need to add more than half, but you want there to be enough liquid to help cook the potatoes and also keep the steak moist but not too much that it makes the gravy too thin.
Add enough salt and pepper to taste too.
Put the pot in the oven for about an hour or until the potatoes are tender to a fork's touch, i.e. falls apart. The softened potatoes should add to the thickening of the gravy. If too liquid, you can add a bit of flour to make it thicker.
Toast some bread and put the hash over it. Enjoy!