Step 1

Pour the broth and water into a tall, heavy-bottom saucepan, and bring it to a boil over medium-high heat.

Step 2

Add the mushrooms, bamboo shoots, ginger, garlic, hot pepper flakes, white pepper, and soy sauce. Stir well, lower the heat to a simmer, and put on the lid.

Step 3

Cut the chicken into thin strips and toss them in the sesame oil. Set aside.

Step 4

In a small bowl, mix the cornstarch and vinegar until smooth. Set aside.

Step 5

Bring the broth back to a boil, then add the chicken. Mix to separate the pieces and cook for 2-3 minutes.

Step 6

Add the cornstarch slurry and stir well. Cook for another 2 minutes.

Step 7

In a small bowl, beat the egg. Then, slowly stir the soup in large circular motions and gently pour the egg into the hot liquid.

Step 8

Keep stirring to create egg streaks in the broth.

Step 9

Cook for another minute, then serve hot with thinly sliced green onions and cilantro (if using).