In a large pot, drizzle a bit of olive oil over medium heat. Once hot, add the diced onion, carrots, and celery. Sauté these vegetables until they are softened, about 5-7 minutes.
Add the minced garlic into the pot and sauté for an additional 1 minute until it becomes fragrant, being careful not to burn it.
Pour the chicken broth into the pot and add the chicken breasts. Increase the heat to bring the mixture to a boil, then reduce to a simmer. Allow it to simmer for about 20-25 minutes, until the chicken is thoroughly cooked and tender.
Carefully remove the chicken breasts from the pot. Using two forks, shred the chicken into bite-sized pieces and return the shredded chicken back to the soup.
Stir in the orzo pasta, cooking according to the package instructions until al dente, usually around 8-10 minutes.
While the soup is simmering, prepare a separate bowl. In it, whisk together the eggs, fresh lemon juice, and lemon zest until it's well combined and frothy.
To temper the egg mixture, slowly add one ladle of the hot soup to the eggs while whisking continuously. This gradual process helps prevent the eggs from curdling.
Once tempered, gradually pour the egg mixture back into the pot, stirring constantly to ensure it evenly incorporates into the soup, imparting that signature creamy lemon flavor.
Season the soup with salt and pepper to taste. Allow it to cook for an additional 2-3 minutes without bringing it back to a boil, to maintain its creamy consistency.
Remove the pot from heat and gently stir in fresh dill or parsley for a burst of fresh aroma and flavor.
Notes
Serve the soup in deep bowls, garnished with an extra sprinkle of chopped dill or parsley. Add a fresh lemon slice on the side for an appealing presentation and a zesty pop of flavor.