Sauté Vegetables: In a large pot, heat the olive oil or butter over medium heat. Add the onion, carrots, and celery. Sauté for about 5-7 minutes until the vegetables are softened. Add the garlic and sauté for another minute.
Add Broth and Seasonings: Pour in the chicken broth, and stir in the thyme, parsley, salt, and pepper. Bring to a boil.
Cook Rice: Add the uncooked rice to the pot. Reduce heat to a simmer and cook for about 15-20 minutes (or according to rice package instructions) until the rice is tender.
Add Chicken: Stir in the cooked chicken and heat through. If using, add the lemon juice for a bit of brightness.
Adjust Seasoning: Taste and adjust the seasoning with more salt, pepper, or herbs as needed.
Serve: Ladle the soup into bowls and garnish with fresh parsley if desired. Enjoy!