Heat the chicken broth in a saucepan over medium-high heat until it gently simmers.
Whisk together the cornstarch and water in a small bowl until smooth.
Beat the eggs with ground white pepper and sesame oil until well combined.
Slowly pour the egg mixture into the simmering broth in a steady stream while stirring gently in a circular motion to form egg ribbons.
Briefly blanch the sliced green onions in boiling water for about 30 seconds, then drain.
Stir the cornstarch mixture again and add it to the soup, stirring continuously until the soup thickens slightly.
Taste and add salt as needed.
Ladle the soup into bowls and garnish with the blanched green onions.
