1. Whisk the eggs in a small bowl until smooth.
2. In another bowl, mix the cornstarch with water to create a slurry.
3. Place the star anise and coriander seeds in a piece of cheesecloth and tie it securely.

1. In a medium saucepan, bring the chicken stock to a boil over medium-high heat.
2. Reduce to a simmer and add the cheesecloth with spices.
3. Let it simmer for 10 minutes, then remove the spices.
4. Stir in the cornstarch slurry and simmer until slightly thickened, about 1-2 minutes.
5. While stirring the broth continuously, slowly drizzle in the whisked eggs to form ribbons.
6. Turn off the heat and let the soup sit for 2 minutes to ensure the eggs are cooked through.
7. Stir in the soy sauce and sesame oil.

Ladle the soup into bowls and garnish with chopped green onion before serving.