The double-lobed kaffir lime leaf has a very fragrant, distinctive taste. Try to purchase fresh leaves, which may then be stored in the freezer. If you can’t get them, substitute tender leaves from other citrus fruit, but the flavour won’t be the same. If you live in a temperate climate, ask at the local nursery. You may be surprised to find they have the trees, labelled kaffir lime or Thai lime. They are pretty hardy and reward you with a year-round source of fresh lime leaves.