Heat the oil in a large saucepan, then add the garlic, ginger and most of the spring onions. Cook for 2-3 mins until softened. Add the corn, water soy sauce and stock cube. Bring to the boil and cook for 5 minutes.
Using a stick blender, whiz the soup until creamy but still textured.
Take a ladleful of soup into a small bowl and mix it with the corn starch to create a paste. Add this to the soup, stir for a minute to thicken, then turn down the heat and add the Shaoxing wine. Slowly drizzle the egg into the soup, using swirling motion. Stir continuously to create little strings
Season with black pepper and add the coriander leaves.
Serve in bowls topped with the reserved spring onion and a drop of rice vinegar, Shaoxing wine or soy sauce.