In a medium pot, bring the water to a boil over high heat. Add sesame oil, Japanese chilli oil, soup stock and a pinch of pepper to the boiling water. Stir well to infuse the flavours.
To create egg ribbons, beat the egg in a bowl. Once the broth is boiling, gradually pour the beaten egg into the broth in a thin, steady stream avoid mixing too much or the soup will become cloudy.
If using dried seaweed or sliced shiitake mushrooms, rehydrate then add them to the soup at this point. Simmer for another minute before serving.
Optional: Once served, add a sprinkling of thinly slicked spring onion to each bowl.
For another great soup recipe take a look at one of our favourites Acorda Alentejana.