In a large pot, combine the chicken broth, red pepper flakes, dark soy sauce, light soy sauce, white pepper, sesame oil, and sugar. Stir well and bring the mixture to a gentle simmer over medium-high heat.
6 cups chicken broth, 1 teaspoon red pepper flakes, 2 teaspoons dark soy sauce, 1 tablespoon light soy sauce, ½ teaspoon white pepper, 1 teaspoon sesame oil, 1 teaspoon sugar
Add the chicken breast to the pot, cover with a lid, and reduce the heat to maintain a low simmer. Cook the chicken for 10 minutes, then carefully remove it from the pot. Use two forks to shred the chicken.
1 chicken breast
To the simmering broth, add the chopped mushrooms, cubed tofu, and shredded chicken. Stir well and allow the soup to simmer for another 10 minutes, letting the flavors meld together.
3 cups mixed mushrooms, 4 ounces firm tofu
In a small bowl, mix the cornstarch with water to create a smooth slurry. While stirring the soup, slowly pour in the cornstarch mixture to thicken it evenly. Continue to stir until the soup reaches your desired consistency.
¼ cup cornstarch, ¼ cup water
Whisk the eggs in a separate bowl. With the soup gently simmering, slowly pour the whisked eggs into the pot in a thin stream while stirring continuously to create delicate egg ribbons.
2 eggs
Taste the soup and adjust the seasoning as needed, adding salt or extra chili flakes for heat. Stir in the sliced scallions just before serving, and enjoy hot.
Salt, 1 scallion