Widely used in Thai and other Asian cuisines, lemongrass is also valued as a medicinal herb because of its antiseptic, antibacterial and antiviral qualities. It has a subtle citrus flavour and is used in teas, soups (key in Thailand's favourite Tom Yum Kung) and stir-fries. It is good with poultry, fish, beef and seafood. Grown in tropical climates, lemongrass is a tall, tough stalky grass. The green tops can be used to flavour custards but it is the lower stalk that is mostly used. To prepare, peel away the tough outer leaves to reveal the pale yellow (almost white) lower section of the stem. Bruise with the flat side of a knife to release the flavour. This lower end is then added to soups and other dishes. To prepare lemongrass for stir-frying, cut the pale section finely across the fibres. Look for fresh lemongrass at your local Asian produce market. It is also often found sold in packets in the freezer section. Packaged fresh lemongrass is sold in some general supermarkets and speciality stores too. If you can’t find any, lemon or lime zest can be substituted but it will not be quite the same, of course.