In a large pot, heat 2 tablespoons of olive oil over medium heat. Add the chopped onion and cook until soft and translucent, about 5 minutes.
Add the minced garlic, diced carrots, and celery to the pot. Sauté for an additional 3-4 minutes until the vegetables are tender.
Stir in the chicken broth and bring to a simmer.
Add the chicken thighs to the pot and cook for about 20 minutes, or until the chicken is fully cooked. Remove the chicken, let cool slightly, then shred it with two forks.
Add the orzo pasta to the broth and cook according to the package instructions, typically about 8-10 minutes.
Meanwhile, in a separate bowl, whisk together the eggs, lemon juice, and dill.
Once the orzo is cooked, reduce the heat to low. Gradually whisk in a ladleful of the hot broth into the egg mixture to temper it, then slowly pour the tempered mixture back into the pot, stirring constantly.
Return the shredded chicken to the soup, and add the chopped parsley. Season with salt and pepper to taste.
Allow the soup to heat through for another 5 minutes, but do not let it boil.
Serve hot, garnished with additional dill or parsley if desired.
Notes
Garnish with additional dill or parsley for extra flavor.