To stir-fry the shrimp, in a wok over high heat, add 1 tablespoon of cooking oil. Add the shrimp and stir-fry for about 1 minute, just until they turn pink. Remove and set aside.
To stir-fry the vegetables and char siu, in the same wok over high heat, add another tablespoon of cooking oil. Add the onion, peas, carrots, and char siu and stir-fry for about 30 seconds until fragrant. Remove and set aside.
To cook the eggs and rice, in the same wok over high heat, add the remaining tablespoon of cooking oil. Pour in the whisked eggs and stir-fry until partially set. Add the overnight rice and stir-fry, breaking up any clumps so each grain separates and heats through.
To combine everything, return the vegetables and char siu to the wok and season with salt, white pepper, and soy sauce. Stir-fry until evenly combined. Return the shrimp and add the scallions. Give everything one final toss and serve hot.
