Oriental-style greens are much more commonplace than they used to be, thanks to the growth of interest in Thai and Chinese cooking. All the ingredients for this dish are now readily available – so get to wok!
Separate the stems from the leaves of the choi sum and cut them into pieces 5cm (2in) long. Blanch the stems in boiling salted water until just tender, then drain well.
Heat a wok or deep frying pan, add the groundnut oil, garlic, ginger, choi sum stems, mushrooms and water chestnuts and stir-fry for 3-4 minutes. Add the choi sum leaves and cook for a minute longer.
Blend the stock with the cornflour to form a paste and stir it into the pan. Stir in the tamari and sesame oil and toss well together. The sauce should form a glaze around the vegetables. Sprinkle over the peanuts and serve immediately.