Quick Chinese Pepper Steak

1 pound 1/2-inch thick round steak
2 tablespoons vegetable oil
1 medium onion, sliced
1 medium green bell pepper, sliced
1 envelope au jus gravy mix
3/4 cup water
4 tablespoons soy sauce
3 cups cooked rice

Cut the meat in half lengthwise with a sharp knife (meat will slice better if slightly frozen), then crosswise into thin slices. Saute the meat, onions and pepper in hot oil in a skillet until the meat is brown. Stir in the remaining ingredients, except the rice. Cook for five minutes, stirring constantly. Serve over rice.