Step 1

Add the corn starch and water together, stir to combine well. Set aside.

Step 2

Add the chicken or vegetable broth and water to a medium-sized soup pot on medium heat. Bring it to boil. Add the tofu and white button mushrooms, cook for 2 minutes. Add the soy sauce, vinegar, dark soy sauce, and black pepper. Stir to combine well. Add in the cornstarch mixture, stir continuously to thicken the soup. Turn off the heat.

Step 3

Swirl the beaten eggs into the soup, count to 10, and then use a pair of chopsticks to stir in a clockwise direction, for 3 times. This will form the silken egg threads in the soup that look very pretty. Add the chili oil and chopped scallions, if using.

Step 4

Dish out and serve immediately.