Leftover cold rice works best in fried rice dishes.
To prepare sauce, combine soy sauce through pepper in a small bowl, stirring with a whisk. Set aside.
To prepare stir-fry, heat vegetable oil in a wok over high heat. Add egg; stir-fry 30 seconds or until scrambled. Add onions and ginger; stir-fry 1 minute. Add shrimp, peas, and rice; stir-fry 3 minutes or until thoroughly heated. Stir in sauce mixture. Serve immediately.