I have a chili recipe with bacon and molasses that would knock your socks off, but that's besides the point. I generally use leftovers to make other dishes. If I have leftover mashed potatoes, I make shepherd's pie, if I have leftover chicken, I make chicken enchiladas (and my recipe is good, it's got roasted portobello mushrooms, etc etc). If I have left over roast or steak, I make chinese noodle soup. Flavour is too good a thing to waste
