A fragrant herb that is used in soups, seafood and meat dishes to produce a lemony flavor, especially in Thai cooking. Fresh lemongrass is pale green in color and has a subtle lemon scent. Its flavor comes from citral, which is an essential oil that is also found in lemon peel. When used in stock, it is cut into strips and bruised to release the flavorful oils. Otherwise the tough outer layers are discarded and the top portion is trimmed off. Also called citronella.