Place the chicken broth in a large pot and slowly bring to a boil. Add the orzo or rice and onion, reduce the heat to medium and simmer.
Meanwhile in a mixing bowl, use a wire whisk to beat the egg yolks until frothy. Continue to whisk the egg yolks while drizzling in the fresh lemon juice.
When the orzo is tender, slowly ladle the chicken broth and orzo into the egg and lemon mixture, beating constantly until all of the soup has been added to the egg and lemon. Adjust seasoning with additional salt and pepper to taste and serve immediately. Makes four servings.