In a large pot or Dutch oven, heat the 1 tablespoon of extra-virgin olive oil over medium heat. Once hot, add the chopped yellow onion, carrots, and celery. Sauté for about 5-7 minutes, or until the vegetables are softened and the onion is translucent.
Stir in the minced garlic, fresh thyme sprigs, and bay leaf. Cook for an additional minute until fragrant.
Add the 8 cups of chicken stock or broth to the pot. Bring the mixture to a gentle simmer, allowing the flavors to meld together beautifully.
Once simmering, add the uncooked long grain white rice. Stir well and let the soup cook for about 15 minutes or until the rice is tender, stirring occasionally.
Next, add the 2 cups of shredded cooked chicken to the pot. Season generously with kosher salt and freshly ground black pepper to taste. Allow the soup to heat through for another 5 minutes.
Before serving, remove the bay leaf and thyme sprigs. Stir in a splash of fresh lemon juice and garnish with chopped parsley.