4boneless skinless chicken breasts(diced; about 2 pounds)
2 ½cupscooked orzo
½cupfresh lemon juice
4large eggs
¼cupminced fresh dill or parsley(optional)
Instructions
In a large soup pot or Dutch oven, heat the olive oil over medium heat. Add the onion and sauté for about 5 minutes until slightly golden. Add the broth, and turn the heat to high. Bring the broth to a simmer.
Lower the heat to medium, and keep the broth at a simmer. Add the diced chicken breasts. Cook for 5 minutes until the chicken is mostly cooked through. Add the cooked orzo.
In a medium bowl, beat the eggs, and then beat in the lemon juice. Working quickly, whisk the egg mixture while you drizzle in a ladleful of the hot broth from the pot (see the note on Tempering Eggs). Drizzle in another ladleful, whisking all the while, then transfer the hot egg-lemon mixture back to the pot, whisking constantly as you add it. Bring to a simmer over medium heat.
Simmer gently for a couple of minutes (do not allow it to come to a boil), then stir in the dill or parsley if using. Serve the avgolemono soup hot.
Notes
Tempering Eggs:What you are doing here is tempering the egg mixture. If you were to add the egg mixture to the pot all at once, even if you whisked very fast, you would still end up with cooked strands of eggs punctuating the soup (in some soups, this is desirable – think about egg drop soup at a Chinese restaurant). Add the hot liquid in slow, steady amounts to the eggs., whisking constantly. The hot broth will blend into the eggs but the slow addition of the broth and the constant whisking keeps them from scrambling. Then, once that mixture has become thick, smooth, and warm, you can whisk it back into the soup and it will simply thicken the whole pot of avgolemono.
You should cook the orzo first; otherwise, it will absorb too much of the broth and also release its starch into the soup. The result will be a too-thick soup. Same with rice, if that's what you're using.
Make sure to add the hot liquid to the eggs in a slow steady stream, whisking all the while.
Cooking the chicken in the broth adds flavor to the chicken, and also enriches the broth.