Crush or finely chop the garlic. Finely grate half the ginger*. Coarsely chop the choy sum. Coarsely chop the pak choy stems, leaving the leaves whole. Bring a medium saucepan of water to the boil for the dumplings.
Step 2 — Make dressing
Combine the garlic, ginger and ¼ tsp chilli flakes* (add more or less to taste) in a large heatproof bowl. Heat the sesame oil in a small saucepan over high heat until hot, then carefully pour over the ginger mixture. Stir in the fish sauce, sweet chilli sauce and 1½ tsp white vinegar. Wipe the pan clean.
Step 3 — Cook rice
Rinse the rice until the water runs clear. Put in the same pan with 250ml (1 cup) water, cover and bring to a simmer over medium heat. Reduce the heat to low and cook for 12 mins or until tender and the water is absorbed. Turn off the heat and stand, covered, for at least 5 mins.
Step 4 — Prep toppings
While the rice is cooking, finely chop the chives. Thinly slice the spring onion on an angle. Combine the fried shallots and sesame seeds in a bowl.
Step 5 — Cook dumplings and greens
Cook the dumplings in the pan of boiling water for 4 mins, then drain. Meanwhile, put the choy sum and pak choy in a large heatproof bowl, cover with boiling water and stand for 3 mins or until tender, then drain.
Step 6 — Toss dumplings and serve
Add the dumplings to the dressing and gently toss to coat. Fluff the rice with a fork. Divide the rice, dumplings and greens among bowls. Drizzle half the oyster sauce* over the greens. Scatter with the fried shallot mixture, chives and spring onion to serve.