Cut the pak choy into thirds, keeping the stems and leaves separate. Thinly slice the radish. Coarsely chop the peanuts.
Step 2 — Pickle radish
Put 3 tsp white vinegar and 1½ tsp sugar in a bowl and stir until the sugar dissolves. Add the radish and toss to combine. Set aside to pickle, tossing occasionally, until needed.
Step 3 — Prep stock
Bring 1L (4 cups) water to the boil in a large saucepan. Add the stock powder and stir to dissolve. Return to the boil and cook for 3 mins to develop the flavour.
Step 4 — Cook dumplings
Add the pak choy stems and dumplings to the stock and cook for 3 mins. Stir in the pak choy leaves and cook for 1 min or until the pak choy leaves are wilted and the dumplings are tender. Remove the pan from the heat. Taste the soup, then season with salt and pepper.
Step 5 — Serve up
Drain the radish, reserving the pickling liquid. Divide the dumplings among bowls (see Kitchen 101), then ladle over the soup. Top with the pickled radish, peanuts and chilli flakes, if using. Drizzle with the sesame oil and a little reserved pickling liquid and enjoy!
Step 6 — Kitchen 101
Handle the cooked dumplings with love and care to ensure they don't break up or burst open.