The leaf of the Kaffir lime plant is more well-known, used in Thai and Indonesian cooking, but you can also use the fruit. The kaffir lime, native to Indonesia and Malaysia, is similar in size (slightly smaller) and colour to what we all know as limes, but has a bumpy skin. The zest can be used in cooking, making sure to avoid the very bitter white pith. As well, the juice of the lime can be used in cooking. It can also be used whole, in curries.