In a large pot, heat a splash of olive oil over medium heat. Add the chopped onion and minced garlic, and sauté until softened, about 3-4 minutes.
Add the diced chicken to the pot and cook until slightly golden, about 5-7 minutes, stirring occasionally.
Stir in the sliced carrots and chopped celery, cooking for another 3 minutes.
Pour in the chicken broth and bring the mixture to a simmer.
Once simmering, add the orzo pasta (or rice) and dried oregano. Cook according to the pasta package instructions, typically 8-10 minutes or until al dente.
In a small bowl, whisk together the eggs and lemon juice until well combined.
To temper the egg mixture, slowly ladle about 1 cup of the hot soup stock into the bowl with the egg and lemon mixture, whisking constantly. This prevents the eggs from curdling.
Gradually pour the tempered egg mixture back into the pot, stirring gently to combine. Be careful not to boil the soup after this step, as the eggs may scramble.
Season with salt and pepper to taste. Remove the pot from the heat and let the soup rest for a couple of minutes to thicken slightly.
Serve hot, garnished with freshly chopped parsley.
Notes
Serve the soup in warm bowls and garnish with a lemon slice and a sprinkle of fresh parsley for a bright and inviting look.