1. Heat 1 tablespoon of sesame oil in a large skillet or wok over medium-high heat. Add the diced chicken pieces and cook, stirring occasionally, until they are golden brown and cooked through, about 5-7 minutes. Remove the cooked chicken from the skillet and set it aside on a plate.

2. Add the remaining 1 tablespoon of sesame oil to the same skillet. Add the chopped yellow onion and cook for 2-3 minutes until it starts to soften. Stir in the minced garlic and grated ginger, cooking for another minute until fragrant.

3. Toss in the frozen peas and carrots blend. Cook for 3-5 minutes, stirring occasionally, until the vegetables are tender-crisp.

4. Add the cold, day-old cooked rice to the skillet, breaking up any clumps with your spatula. Stir everything together well, ensuring the rice is evenly coated with the oil and mixed with the vegetables. Continue to cook for about 3-4 minutes, allowing the rice to heat through and slightly crisp up.

5. Pour in the soy sauce and oyster sauce (if using). Stir well to distribute the sauces evenly throughout the rice. Make sure every grain gets a coating of that savory goodness.

6. Push the rice and vegetables to one side of the skillet, creating a clear space. Pour the lightly beaten eggs into the empty space. Scramble the eggs with your spatula until they are just set, then break them into smaller pieces and mix them into the rice mixture.

7. Add the cooked chicken back into the skillet with the rice and vegetables. Stir everything together until the chicken is thoroughly heated through.

8. Remove the skillet from the heat. Garnish generously with thinly sliced green onions before serving immediately.