Heat cooking oil in a large skillet or pot over medium heat.

Add the chopped onion and cook until softened, about 3-4 minutes.

Add the chicken pieces and cook, stirring occasionally, until browned on all sides, about 5-7 minutes.

Stir in the minced garlic and cook for 1 minute until fragrant.

Add the uncooked rice to the skillet and stir for 1 minute to lightly toast it.

Pour in the broth or water, add salt and pepper, and stir everything together. Bring to a simmer.

Reduce heat to low, cover the skillet, and cook for 15 minutes.

Stir in the mixed vegetables, cover again, and cook for another 5-10 minutes, or until the rice is tender and liquid is absorbed. Cooking time may vary depending on the rice and vegetables used.

Remove from heat and let stand, covered, for 5 minutes before serving.

Serve hot, optionally topped with fresh herbs or grated cheese if using.