You can precook the mushrooms if you're using fresh mushrooms.it's just so those mushrooms don't release extra water in the soup. In the soup pot/pan add all the ingredients as well as cooked mushrooms except for the garnishes. Mix very well.
Add 3 glasses of water and put it on the stove.
bring it to a simmer on high heat until the soup thickens and chicken and prawn are cooked.
Immediately garnish and serve hot. don't wanna overcook it as it tends to make the prawns rubbery and tough. enjoy by itself or with some wontons and a bowl of steamed rice.