Heat the olive oil in a large soup pot over medium heat. Add the chopped onion, carrot, and sliced celery. Sauté until the vegetables are soft and fragrant, about 5 minutes, with gentle bubbling and a mixture of sweet aromas.
Add the minced garlic, dried thyme, and sage to the vegetables. Cook for another minute until the garlic is fragrant and lightly golden, with sizzling sounds and a warm kitchen aroma.
Pour in the chicken broth and bring the mixture to a gentle simmer. Scoop in the bite-sized chicken pieces, stirring to combine. Reduce the heat to medium-low, cover loosely, and let it simmer for about 10 minutes, until the chicken is cooked through and the flavors meld.
Once the chicken is cooked, add the uncooked rice to the pot. Stir well, then cover and simmer for another 15 minutes, or until the rice is tender and the soup thickens slightly, with the rice appearing plump and the broth turning velvety.
Season the soup with salt and pepper to taste. Taste and adjust the seasoning as needed, ensuring a balanced, flavorful broth, and watch for a slightly thicker, hearty consistency as the rice releases starch.
Serve the soup hot, garnished with fresh herbs if desired, for a comforting bowl that shows a rich, colorful mixture of vegetables, tender chicken, and fluffy rice floating in a velvety, flavorful broth. Enjoy the cozy, autumn-inspired flavors with each spoonful.