To prepare, in a bowl, whisk the eggs until well combined. In another bowl, mix the cornstarch and water until smooth.
To heat the broth, in a pot over high heat bring the chicken stock and salt to a simmer. Stir in the slurry and continue stirring until the soup thickens slightly and reaches a full boil.
To create the egg flowers, reduce the heat to medium so the soup maintains a gentle boil. Slowly drizzle the eggs into the pot in a thin stream in one direction. For thinner egg ribbons, stir gently as you pour in the eggs. For larger egg ribbons, wait a few seconds before stirring so the eggs have time to set. To finish the soup, bring the heat back to high briefly and add the white pepper, sesame oil, and scallions. Serve immediately while hot.