The kaffir lime belongs to the citrus family. It resembles a lime with bumpy skin. Native to Indonesia, it is commonly used in Thai cuisine and that of other countries bordering the Indian Ocean. Kaffir lime develops a flavor similar to that of lemongrass, as do the leaves of the plant, which also have a high content in essential oils. It is picked green, before ripening completely, when its concentration of flavor is at its peak.
Choose kaffir limes that are firm and slightly shiny. Their bumpy skin should be intense green, without yellowing (sign of ripeness) or dried parts. Kaffir limes are sold in Asian grocery stores and also in the tropical fruit sections of some supermarkets. Their leaves are sometimes available fresh, but it is easier to fine them frozen or dried.
The flavor of kaffir lime can be used to balance the heat in curries. Its strong aroma and slight bitterness act as a flavor enhancer.
The very acidic and bitter flesh of the kaffir lime is not used, only a few drops used very sparingly. Its zest is used to flavor a large number of sweet and savory preparations. This should be grated very carefully to avoid taking off the very bitter pith. The leaves are used in marinades, sauces, or to flavor the cooking water of rice or other cereals.
Kaffir limes can keep for a week in a fruit basket, and up to two weeks in the vegetable crisper drawer of the refrigerator. It can be frozen; the frozen zest is easier to grate.
Like all citrus fruits, kaffir lime is high in vitamin C. But because its juice is not used, this is not really of much importance. Kaffir lime essential oil is used in phytotherapy.