In a large pot, combine the chicken broth, diced chicken thighs, carrots, celery, onion, and minced garlic.
Bring the mixture to a boil over medium-high heat, then reduce to a simmer. Cover and cook for about 20 minutes, or until the chicken is cooked through and tender.
Remove the chicken from the pot and shred it using two forks. Return the shredded chicken to the pot.
Stir in the orzo pasta and oregano. Cook for an additional 10 minutes, or until the orzo is al dente.
In a separate bowl, whisk together the eggs, lemon juice, and lemon zest until well combined.
Slowly ladle about 1 cup of hot broth from the soup into the egg mixture while continuously whisking to temper the eggs.
Gradually stir the egg mixture back into the soup, avoiding boiling to prevent curdling. Cook for an additional 2-3 minutes.
Season with salt and pepper to taste. Remove the pot from heat and let it sit for a minute.
Notes
Ladle the soup into bowls and garnish with fresh parsley and additional lemon slices for a vibrant presentation.