Heat the vegetable oil in a large skillet over medium-high heat. Add the diced chicken and cook until no longer pink, about 5 to 6 minutes. Season lightly with salt and pepper.

Stir in the minced garlic and cook for 30 seconds until fragrant. Add the frozen mixed vegetables and stir-fry for 3 to 4 minutes until they begin to soften.

Push the chicken and vegetables to one side of the skillet. Pour the beaten eggs into the empty space and scramble them until just set.

Add the cooked rice and soy sauce to the skillet. Stir everything together and cook for another 3 to 4 minutes, breaking up any rice clumps, until the mixture is heated through and evenly coated.

Remove from heat and sprinkle the sliced green onions over the top before serving.