This vegetable is grown and used primarily in northern China. The Cantonese of Hong Kong treat it as an onion and stir-fry it with meats. The leeks found in Hong Kong are large and cylindrical, resembling a giant spring onion with a white husk like garlic. Conventional British leeks are a good substitute. Leeks have a mild, slightly sweet onion flavour. To use, cut off and discard the green tops and roots and slice the leeks in half lengthwise. Wash them well. Store them as you would spring onions.