Fried rice
Fried rice is the ultimate way to use up leftovers. It's not only a delicious way to use up leftover chicken, but it also tastes better when made with old leftover rice. It's also ridiculously simple. All you need for a delicious chicken fried rice is scallions, garlic, soy sauce, sesame oil, rice, eggs, and, of course, chicken.
In a wok or large nonstick skillet, sauté the scallions and garlic in oil, then add the rice and chicken and cook until heated through and the rice is coated in an even layer of oil. Push the rice to the side of the pan, then add the eggs to the oil and cook until mostly done, then combine with the rice. Make a tasty lunch by seasoning everything with soy sauce and sesame oil. Once you've mastered the basic technique, you can create an infinite number of variations by varying the vegetables and seasonings.