In a 4-quart Dutch oven, heat olive oil over medium heat. Add onion and cook until softened, about 5 minutes. Add chicken broth and bring to a boil. Add orzo and cook until tender, 8 to 10 minutes. Season to taste with salt and pepper.Advertisement
Meanwhile, in a medium bowl, whisk together eggs and lemon juice. Slowly add 1 cup of the hot broth to the egg mixture while whisking. Then, slowly stir the egg mixture into the broth in the Dutch oven. Add chicken. Cook and stir until nearly boiling, 1 to 2 minutes. (Do not boil.)
Serve immediately, seasoned to taste with salt and pepper and garnished with fresh dill.