Season the chicken pieces with salt and pepper.
Heat 1 tablespoon vegetable oil in a large non-stick skillet or wok over medium-high heat. Add the chicken and cook, stirring occasionally, until no longer pink and cooked through, about 5–6 minutes. Remove the chicken to a plate and set aside.
If needed, add a bit more oil to the skillet. Pour in the beaten eggs and cook, stirring gently, until they are just set. Transfer the scrambled eggs to the plate with the chicken.
Add the remaining 1 tablespoon vegetable oil to the skillet. Sauté the minced garlic and the white parts of the green onions for about 1 minute, until fragrant.
Add the chilled cooked brown rice to the skillet and break up any clumps with the spatula. Stir-fry the rice for 2–3 minutes until warmed through.
Drizzle the soy sauce and sesame oil over the rice, then add the thawed peas and carrots, cooked chicken, and scrambled eggs. Stir everything together and cook for another 2–3 minutes until heated through.
Stir in the green parts of the green onions, taste, and adjust seasoning with salt and pepper if needed. Serve hot.
