Flowering chives are very different from the mild-mannered variety used in the West - the flavour is strong and pungent. Unlike the Western chive, which is usually reserved for use as a garnish (on vichyssoise, for instance), the Chinese chive is grown to be eaten.
The chives, which have bright green, long, hollow stalks - get their name from the flower bud at the tip. When you buy chives, the stalks should be glossy and firm, rather than flaccid, and the bud (which is edible) should be tightly closed - if it's open, it means the vegetable is old and will be less tender. Usually, the entire stalk is edible, although the base is tougher than the tip and should be cooked for slightly longer. Occasionally, you'll come across some flowering chives where about 2cm of the base feels hard and woody; it's better to trim that off and discard it because it will be too tough to eat.
Although flowering chives are available all year, they're popular during the cooler months because they're considered warming.
For a simple stir-fry dish, cut flowering chives into 5cm lengths, keeping the tougher base parts separate from the rest of the stalks. Heat a little oil in a wok, add the base of the stalks and stir-fry for a couple of minutes. Add the rest of the vegetable and a splash of soy sauce and stir-fry until crisp-tender. Stir in a little oyster sauce and sesame oil just before removing the chives from the wok. If you want a more substantial dish, add some sliced pork (marinated with soy sauce, rice wine and a little sugar) or squid pieces near the beginning of the process, so it's cooked through when the vegetable is ready.