Gather all your ingredients and keep them within reach. Dice the onion, mince the garlic, and chop the carrots and celery for easy addition.
Heat the large heavy-bottomed pot over medium heat, then add a splash of oil to coat the bottom. Once shimmering, add the diced onion and minced garlic. Sauté for 2-3 minutes until fragrant and translucent, filling your kitchen with a warm aroma.
Add the diced carrots and celery to the pot. Cook, stirring occasionally, for about 5 minutes until the vegetables soften slightly and release their aroma.
Pour in the chicken broth and bring it to a gentle simmer. Stir in the rice and add the chicken pieces. Cover the pot, then reduce the heat to medium-low. Let everything simmer for about 20 minutes until the rice is tender and the chicken is cooked through.
Check that the chicken is fully cooked—juices should run clear, and no pink should remain inside. Taste the broth and season with salt and pepper as needed.
Turn off the heat and squeeze in fresh lemon juice, stirring gently to brighten the flavors and bring a lively finish to the soup.
Give the soup a final stir, then ladle into bowls. Serve hot, with an extra squeeze of lemon or fresh herbs if desired for an added touch of brightness.