In a big soup pot, cook finely chopped celery, carrots, and onions in butter and olive oil over medium-high heat for 5-7 minutes or until veggies are tender.
Stir in minced garlic and cook for about 30 seconds until it smells amazing. Then, add flour and cook for another minute until it’s lightly browned.
Pour in the chicken broth, stirring well until the flour dissolves. Add oregano, thyme, salt, black pepper, and bay leaves to the pot.
Put the uncooked chicken breasts and washed rice into the pot. Bring the soup to a boil, then reduce the heat to a simmer. Cover and let it simmer for 20-25 minutes until the chicken is cooked and the rice is tender.
Take out the chicken breasts, cut them into bite-sized pieces, and return them to the soup.
Squeeze a bit of lemon juice into the soup to brighten the flavors. Adjust the taste with salt and pepper, if needed.
Just before serving, sprinkle chopped fresh parsley over the soup for added freshness and color.
Ladle the chicken and rice soup into bowls and enjoy!
Store leftovers in an airtight container in the fridge for up to 3 days or freeze for up to 3 months.