1. Heat the olive oil in a large pot or Dutch oven over medium heat. Add the cubed chicken and cook until lightly browned on all sides, about 3-4 minutes. Remove the chicken from the pot and set aside.

2. In the same pot, add the chopped onion and cook until softened and translucent, about 3-5 minutes. Stir in the minced garlic and cook for another minute until fragrant, being careful not to burn it.

3. Pour in the diced tomatoes (undrained) and chicken broth. Stir in the rinsed brown rice, dried oregano, dried basil, and black pepper. Bring the mixture to a boil.

4. Once boiling, reduce the heat to low, cover the pot tightly, and let it simmer for 20 minutes. The rice will begin to absorb the liquid and cook.

5. After 20 minutes, stir the reserved chicken back into the pot. Add the frozen mixed vegetables. Stir gently to combine everything.

6. Re-cover the pot and continue to simmer for another 5-10 minutes, or until the rice is tender, the chicken is cooked through (no longer pink inside), and the vegetables are heated through. If the mixture seems too dry, you can add a splash more broth or water.

7. Remove the pot from the heat and let it rest, covered, for 5 minutes. This allows the flavors to meld and the rice to fully steam.

8. Ladle the one-pot meal into bowls, garnish with fresh chopped parsley if desired, and serve warm.