To prepare the ingredients, chop the scallions and bok choy. In a bowl, whisk the eggs until smooth. In a small bowl, mix the cornstarch with water to form a slurry.
To start the soup, in a pot over high heat, add the chicken stock and salt, then bring to a gentle simmer. Add the bok choy and cook for about 30 seconds until just softened.
To cook the seafood, add the shrimp and scallops, then cook for about 1 to 1½ minutes until they turn opaque.
To thicken the broth, stir the slurry, then pour it into the soup. Let it come back to a gentle simmer until slightly thickened.
To create the egg ribbons, reduce the heat to medium. Slowly drizzle in the eggs in a circular motion. Let them set briefly, then gently stir to form ribbons.
To finish, add the scallions, sesame oil, and white pepper. Stir gently and serve hot.