Crush or finely chop the garlic. Peel and finely grate the ginger. Thinly slice the spring onion on an angle. Coarsely chop the pak choy, keeping the stems and leaves separate.
Step 2 — Prep stock
Bring 1.5L (6 cups) water to the boil in a medium saucepan. Crumble in 3 stock cubes* and stir to dissolve.
Step 3 — Make soup base
Add the garlic, ginger, three-quarters of the spring onion, half the sesame oil, 1 tsp sugar and 2 tsp soy sauce to the stock and bring to a simmer over high heat. Reduce the heat to medium and simmer for 4-5 mins to develop the flavour.
Step 4 — Make chilli vinegar
Meanwhile, heat ½ tsp chilli flakes* and 1 tbs oil in a small saucepan over low heat and cook, stirring, for 2-3 mins until fragrant. Remove from the heat and carefully stir in the remaining sesame oil, 1 tbs white vinegar, 2 tsp soy sauce and 1 tsp sugar (take extra care when adding liquid to the hot pan as the oil can spit and the steam created is very hot).
Step 5 — Cook dumplings
PORK DUMPLINGS OPTION Add the pork dumplings to the soup base, bring to the boil and cook for 1 min. Add the noodles and return to the boil.
Step 6 — Get ready to serve
Add the pak choy stems to the soup and cook for a further 3 mins or until the noodles are tender. Add the pak choy leaves and stir for 30 secs or until wilted. Divide the soup among bowls. Drizzle with a little of the chilli vinegar and scatter with the remaining spring onion. Serve with the remaining chilli vinegar.