Pour cooking oil into a wok or large skillet. (Add more oil as necessary during cooking.) Preheat over medium-high heat. Stir-fry carrots in hot oil for 2 minutes. Add onion; stir-fry for 2 to 3 minutes or until crisp-tender. Remove vegetables from the wok.
Add apples to the hot wok; stir-fry for 2 minutes. Sprinkle with sugar and salt. Carefully add water. Cover and cook over medium heat for 3 minutes or until apples are just tender. Return cooked vegetables to the wok. Cook and stir until heated through. Sprinkle with nutmeg, if desired. Serve immediately. Makes 4 servings.