Okay, Chinese New Year isn't technically until tomorrow, but it is cold, and I am hungry, and I love Hot 'n Sour soup!
So here is the Ancient Chinese Secret.
Chicken stock, vinegar, and hot sauce. Yep, that's it! Then add whatever you like, or recognize (or not) as UFOs (unidentified floating objects) in your soup. That may, or may not be -- tofu, onions, garlic, bamboo shoots, egg, chicken, mushrooms (and the Chinese have so many kinds to choose from), seaweed, carrots, cabbage . . . the list goes on and on, and that is half the fun.
BTW -- nothing is better for the cold, and/or flu than Hot 'n Sour Soup, and there is an especially nasty strain circulating this season.
So cook up a big pot of this soup, and dispense liberally!