Crush or finely chop the garlic. Finely slice half the chilli*, discarding the seeds if less heat is desired. Crumble 1 stock cube* into a heatproof jug, add 750ml (3 cups) boiling water and stir to dissolve.
Step 2 — Start soup
Heat a drizzle of oil in a medium saucepan over medium-high heat. Stir-fry the slaw mix for 2 mins or until slightly softened. Add half the garlic and half the Chinese barbecue seasoning and stir-fry for 1 min or until fragrant. Carefully add the stock and 3 tsp soy sauce. Bring to the boil, reduce the heat to medium and cook, covered, for 5 mins to develop the flavour.
Step 3 — Make sesame chilli oil
Meanwhile, heat the sesame oil in a medium frypan over medium heat. Cook the chilli, remaining garlic, remaining Chinese barbecue seasoning and ½ tsp sugar, stirring, for 1 min or until fragrant. Transfer to a small heatproof bowl, add 1 tbs white vinegar and 1 tsp soy sauce and stir to combine. Wipe the pan clean.
Step 4 — Cook dumplings
Heat a generous drizzle of oil in the same pan over medium-high heat. Cook the dumplings, without turning, for 2-3 mins until golden on one side. Carefully add 60ml (¼ cup) water (take extra care adding water to the hot pan as the oil can spit and the steam created is very hot). Cover and steam for 3 mins or until the dumplings are tender.
Step 5 — Finish soup
While the dumplings are cooking, coarsely chop the pak choy. Add to the soup and cook for 2 mins or until wilted.
Step 6 — Get ready to serve
Divide the soup and dumplings among bowls. Drizzle with the sesame chilli oil and scatter with the sesame seeds to serve.