In a small bowl, toss the pork pieces with 1 tsp soy sauce and 1/2 tsp cornstarch. Let it marinate for at least 10 minutes while you prepare other ingredients.
Heat 1 tbsp of vegetable oil in a large wok or skillet over medium-high heat. Add the marinated pork and stir-fry until browned and cooked through, about 3-5 minutes. Remove the pork from the wok and set aside.
Add a little more oil to the wok if needed. Pour in the beaten eggs and cook, stirring gently, until scrambled. Break the eggs into smaller pieces and set aside with the pork.
Add the diced onion and the white parts of the green onions to the wok. Stir-fry for 1-2 minutes until the onion is softened and fragrant.
Add the minced garlic and cook for another 30 seconds until fragrant, being careful not to burn it.
Add the thawed peas and carrots to the wok and stir-fry for 1-2 minutes until heated through.
Add the cooked rice to the wok. Break up any clumps with your spatula and stir-fry for 2-3 minutes until the rice is heated through and slightly toasted.
In a small bowl, whisk together 3 tbsp soy sauce, oyster sauce, sesame oil, and white pepper (if using). Pour this sauce mixture over the rice.
Add the cooked pork and scrambled eggs back into the wok. Stir everything together to combine and ensure the sauce is evenly distributed. Cook for another 2-3 minutes, stirring constantly, until everything is well combined and heated through.
Stir in the green parts of the green onions just before serving.