In a large pot, heat the olive oil over medium heat. Add the chopped onion and sauté until it becomes translucent, about 5 minutes.
Add the minced garlic and sauté for an additional 1 minute, until fragrant.
Pour in the chicken broth and bring to a boil. Once boiling, add the arborio rice and cook according to package instructions until tender, about 18 minutes.
If using, add the shredded chicken to the pot in the last 5 minutes of rice cooking time to heat through.
In a separate bowl, whisk together the eggs and lemon juice until combined.
Slowly ladle a cup of the hot soup broth into the egg and lemon mixture, whisking continuously. This tempers the eggs and prevents them from curdling.
Gradually add the tempered egg mixture back into the pot, stirring constantly to incorporate without cooking the eggs into curds.
Stir in the chopped dill and season with salt and pepper to taste.
Allow the soup to heat through for another minute, then remove from heat.
Notes
Serve in warm bowls, garnished with a slice of lemon and a sprinkle of fresh dill on top for a burst of color.