Rinse the rice in a large sieve until the water drains nearly clear. Set aside to drain.
Heat 2 tablespoons of olive oil over medium heat in a largeDutch oven or soup pot, at least 4-quart capacity. Add chicken thighs and cook until just opaque on each side, with barely any browning.
Move the chicken to the side of the pan and add onion, celery and garlic. Stir until the onion begins to turn translucent, then add the rinsed and drained rice. Stir all to combine and continue cooking over medium heat until the rice begins to turn opaque, about 3 – 4 minutes.
Add the chicken broth, cover with a tight-fitting lid and bring to a boil. Once boiling, reduce the heat to achieve a slow simmer. Let simmer for about 25 minutes until the chicken is cooked through and the rice has become soft and begins to open (bloom).
Remove the chicken pieces and coarsely chop or shred. Return the chicken to the soup and add the freshly squeezed lemon juice.
Once the soup returns to a slow simmer it is ready! Serve with a generous flourish of chopped fresh parsley and/or mint leaves. A thin slice of lemon atop will signal the lemony burst of flavor.