First, prepare the dried fungus and shitake mushroom. Place the fungus and shitake mushroom in a bowl, cover with warm (not boiling) water and set aside for 20-30 minutes. Rinse & drain, finely slice & set aside.
In a bowl, whisk together the egg, sesame oil and 1 teaspoon of water. Set aside.
Heat a wok or soup pot over a medium heat. Add the garlic & ginger paste and warm through for 30 seconds. Add the chicken stock, salt, msg, sugar, light soy sauce, dark soy sauce & chilli bean sauce.
Add the prepared fungus & shitake mushroom. Add the cooked pork, bamboo shoots & sliced carrot. Bring to the boil & simmer for 2-3 minutes. Add the white pepper & black vinegar and mix well.
In a bowl, combine the potato starch and 2 tablespoons of water and mix well. Add slowly to the simmering soup, mixing well. Add as much as needed to achieve the thickness / consistency you prefer.
Slowly drizzle the egg mix into the soup (only around half of the egg mix will be needed). Allow the egg to sit in the soup for 20-30 seconds before stirring gently to create the classic 'egg drop' ribbon effect in the soup.
Add the sliced spring onions, ladle the soup into a serving bowl and serve.
Hot & sour soup typically comes with a selection of meats including chicken, pork & shrimp from Chinese takeaways. This recipe uses cooked char-siu pork but you can, of course, use whichever selection of meats you prefer. If using raw meat, cut the meat into small pieces in order to ensure that it cooks quickly and simmer for an extra 1-2 minutes in the soup until fully cooked.