For the chilli oil, heat the sesame oil in a small frying pan over high heat. Add the garlic, chilli and sesame seeds and cook for 30 seconds. Pour into a heatproof bowl, season with 1 teaspoon of sugar and salt and set aside to infuse and cool.
Combine the stock, mushrooms, vinegar, soy and sugar in a large saucepan over medium heat. Bring to a simmer and cook for 10 minutes.
Increase the heat to high, add the dumplings and cook for 5 minutes. Add the bok choy and cook for a further 2 minutes.
Divide between bowls and serve with chilli oil and shiso.
