Add the oil to a Dutch oven over medium-high heat then add the chopped onion, carrot, and celery. Cook until translucent and tender.
Add the rice and chicken broth to the pot and bring to a boil. Reduce the heat to a simmer and cook for about 15 minutes or until the rice is cooked through.
Meanwhile in a small bowl beat the egg together with lemon juice.
Add the shredded chicken to the pot, then add about a ladle of the soup broth to the egg mixture and stir. Pour the egg mixture into the soup. You will notice the soup thickening up. Season with salt and pepper as needed and if you feel the soup needs more lemon, add more lemon juice as desired.
Garnish with lots of parsley and lemon slices.
