THE Cantonese call it kiu choi (pronounced que choy); the Japanese call it rakkyo. In Taiwan, ask for baker's garlic; it's scientific epithet is Allium chinense. Its season comes on the heels of Ching Ming festival and aficionados of this delightful chive-like scallion are savouring its special qualities. At $4 per catty, it's a cheap thrill. Seasonality is one of the joys of Hongkong's markets and limited availability sharpens appreciation for whatever particular, inimitable characteristics such seasonal vegetables have. Kiu choi, available only in the spring, is a leafy member of the onion family. Seeds are sown in early winter; by March they have developed into slender white bulbs with even more slender green leaves 20cm to 30cm long. They grow in dense clumps. Harvested just as they grow, they typically also appear in the markets in large clumpsor mounds, never as individuals. This characteristic clumping growth habit distinguishes kiu choi from spring onions, which are larger and sold as individual stalks, and from garlic chives which are sold without a bulb. In taste, kiu choi resembles scallions and has a predictable mild pungent flavour. Its most special characteristic is a certain crispness in the bulb which survives light cooking. The entire plant can be eaten from bulb to leaf tips. Most Cantonese, however, consider the greens too tough to eat, cutting the leaves off about mid-stalk (where the green begins) and discarding the upper portion. Buying and preparation: Select those with the most green leaves per plant. Wash well. Remove dead and yellowing leaves; chop them off at the neck; discard the whites and reserve the greens for cooking. Cooking: Stir-frying is the cooking method of choice; peapods and beef are the most widely recommended ingredients, although eggs, chicken, fish and squid also go well with it. Usage: Cooks familiar with Western ''chives'', another slender, clumping member of the onion tribe - will find that kiu choi can be used in virtually all the same ways. With its mild pungent flavour, tiny size, and crisp texture, it can be added to salads, salad dressings, herb butters, sauces and marinades. Minced, it can also be used to garnish virtually any savoury dish. But it is not for greens alone that kiu choi is grown. If left in the fields for an entire year, the bulbs triple in size. They are harvested, pickled in vinegar, and subsequently sold as suen kiu tau (meaning the ''sour head of kiu choi'') in local market groceries or as ''pickled scallions'' or ''pickled leeks'' (both misnomers) in bottles and jars. Martha Dahlen, an American botanist and food-writer, has lived in Hongkong for 14 years. She is the author of A Cook's Guide To Chinese Vegetables, (Guidebook Co, $110).
