In a large pot, combine chicken broth, fresh lemon juice, shredded carrots, finely chopped onion, finely chopped celery, chicken soup base, and ground white pepper. Bring to a rolling boil over medium-high heat, then reduce to low and simmer for 15–20 minutes.

In a small bowl, mix margarine and all-purpose flour to form a smooth paste. Gradually whisk this paste into the simmering soup, stirring to avoid clumps. Cook for an additional 8–10 minutes until thickened.

Beat the egg yolks until pale, then gradually whisk in a ladleful of the hot soup. Return the egg mixture to the pot, stirring continuously over low heat without boiling.

Add the cooked white rice and diced cooked chicken to the pot, stirring gently and heating through for about 3–5 minutes.

Ladle the soup into bowls garnished with lemon slices and fresh herbs, serving immediately.