Pour the stock in a medium-sized saucepan then add the sliced ginger, star anise and Chinese five spice. Simmer the stock gently for about half an hour to let the flavours develop.
Crack the eggs into a jug and whisk till well combined.
Finely chop the spring onions or chives. Set aside. When you are ready to eat, remove the stock from the heat. Using a slotted spoon, remove the star anise and ginger slices. Carefully pour the egg into the hot broth, whisking all the time, quickly and thoroughly until thin ribbons of egg appear and all of the raw egg mix is added. Add the sesame oil and season with salt and pepper to taste. Pour into bowls and scatter the chives and sesame seeds over the top. This soup doesn’t keep or reheat well so serve right away.