Put all of the ingredients in a large wok or saucepan (except the cornflour paste, sesame oil and eggs), plus 1 1/2 tsp salt. Slowly bring to the boil, turn down the heat and simmer for 3 mins. Taste and add a little more vinegar or chillies, if you like.

Give the cornflour paste a good mix, turn up the heat to medium and slowly add the paste to the soup, stirring throughout until it coats the back of a spoon. Turn off the heat and slowly pour in the beaten egg, stirring as you pour. Add the sesame oil and serve.