In a medium bowl, combine the sliced chicken with soy sauce, Shaoxing wine, cornstarch, and vegetable oil. Mix well and let marinate for 5–10 minutes.
In a separate small bowl, whisk together soy sauce, dark soy sauce, sesame oil, chicken bouillon powder, and pepper to make the sauce. Set aside.
Heat 1 teaspoon of vegetable oil in a large skillet or wok over medium-high heat.
Add the marinated chicken and cook until fully cooked and lightly golden, then remove from the pan and set aside.
Add another teaspoon of oil to the skillet and sauté the garlic and shallots for a few seconds until fragrant.
Stir in the frozen vegetables and cook briefly until heated through. Push everything to one side of the pan.
Add the remaining oil to the empty side of the skillet and pour in the beaten eggs. Let them sit for a few seconds before scrambling into small pieces.
Add the cold rice and cooked chicken back into the skillet. Toss everything together until evenly combined.
Pour the sauce around the edges of the pan and let it cook for a few seconds before mixing it into the rice.
Stir-fry everything together until the rice is evenly coated and slightly toasted.
Serve warm and garnish with green onions if desired.