First scrub the clams, removing any debris from the shells and discarding any that remain open when tapped against a hard surface.
Heat a wok over a high heat until it starts to smoke and then add the groundnut oil. Add the ginger, dried shrimps (if using) and mushrooms and stir-fry for a few seconds.
Tip in the clams and stir-fry for one minute.
As the shells start to open up, add the rice wine or dry sherry.
Pour in the stock and cook for three to four minutes or until all the shells have opened. Discard any that remain closed.
Season to taste with salt and pepper and thicken the cooking liquid with the cornflour paste. Toss in the coriander and let it wilt slightly, then remove from the heat, transfer to a large dish and serve immediately.
Ching's Fast Food is published by HarperCollins, priced £20.