To prepare the ingredients: Chop the scallions. Crack the eggs into a gravy boat or bowl and beat until well combined. In a separate small bowl, combine the cornstarch and water to make a slurry.
To season the soup: Pour the unsalted chicken stock into a pot over high heat. Season with a pinch of salt and bring to a boil.
To cook the shrimp: Add the shrimp and cook until they turn pink. Remove them from the soup and set aside while you finish the broth and egg ribbons.
To thicken the soup: Give the cornstarch slurry another stir, then slowly stir it into the chicken stock. Let the soup return to a full boil until lightly thickened and silky. Reduce the heat to medium.
To make the egg ribbons: Slowly drizzle the beaten eggs into the soup in a circular motion. For thinner ribbons, gently stir as you pour. For thicker ribbons, wait a few seconds for the eggs to set before gently stirring.
To finish and serve: Return the shrimp to the soup. Add the scallions, sesame oil, and white pepper. Gently stir and serve immediately.