How to Make It
In a small bowl, cover the lily buds with boiling water and let stand until softened, about 10 minutes. Cut off and discard the tough tips. In another small bowl, cover the dried tree ear fungus with boiling water and let stand until softened, about 20 to 30 minutes. Rinse and coarsely chop.
Meanwhile, in a large saucepan, bring the broth to a boil. Add the vinegar, soy sauce and salt. In a small bowl, whisk the cornstarch with 3 tablespoons of water, then add the mixture to the boiling broth, stirring constantly. Let the broth return to a simmer and cook until soup thickens, about 3 to 4 minutes.
Beat the eggs with a pinch of salt. Bring the soup to a full rolling boil, and using a circular motion, pour the beaten eggs into the soup. Wait 5 seconds, then turn off the heat and stir the pot to distribute the eggs throughout the soup.
Add the lily buds, tree ear fungus, bamboo shoots, chicken, tofu and white pepper. Simmer over medium heat until the flavors meld, about 2 minutes. Season with soy sauce, vinegar and salt.
Divide the soup among 4 bowls. Drizzle each with sesame oil and garnish with scallion and cilantro.