Clean the dried day lilies, soak them in warm water for about 20 minutes. Cut off the hard, tough tip of the stem and then cut the day lilies in half lengthwise.
Clean and soak the wood ear mushrooms in warm water for about 20 minutes, then cut into small pieces.
Bring the chicken broth to a boil and then add the pork, skimming the surface of any fat. Cook the pork for 3-4 minutes, until the broth comes to a boil again.
Add the tofu, mushroom pieces, bamboo shoots, and day lilies.
Let the pot return to a boil, then reduce heat to maintain a low boil.
Add the soy sauce, spices, vinegar, salt and sugar.
Taste the soup, adjusting the vinegar (you may need to modify up or down by an ounce) for the "sour" and salt for balance.
Mix the corn starch and water to create a paste for thickening.
Add the corn starch mixture slowly, stirring constantly.
Drizzle the beaten eggs in slowly while stirring, so that you get "strings" of egg.
Turn off the heat.
Ladle the soup into bowls, then garnish with 1/2 tsp of scallion per bowl and a drizzle of sesame oil.