Rough and tough
The kaffir lime is the shar pei of the citrus world: it's wrinkled, bumpy and has an appearance only its mother could love. It's not the juiciest of limes, but that doesn't matter, because the plant is useful primarily for its tough but beautifully scented leaves, and for the fruit's distinctly flavoured and aromatic zest. Both the leaves and zest are available dried (the leaves, especially, maintain a surprising amount of their scent) but they're easy enough to source fresh at Southeast Asian grocery stores. Kaffir lime is used in Indonesian, Malaysian and Thai cuisines.
Fresh kaffir lime leaves should be shiny, pliable and smooth. The fruit - golf ball-sized and larger - should be evenly green and glossy, rather than matte.
The zest is a delicious addition to plain butter cookies - grate it finely (preferably on a rasp-type grater) and add it to your favourite sable biscuit or shortbread recipe. For an alcoholic drink, infuse the kaffir lime zest and finely shredded leaves in a bottle of good-quality vodka and leave for several weeks. Strain out the solid ingredients before storing the bottle of alcohol in the freezer so it can be consumed in shots, or used in cocktails.
Because kaffir lime leaves are tough, they're only edible if finely shredded. They're delicious in Thai-style seafood custard, made by pounding white-fleshed fish with shrimp to a paste, then mixing with coconut milk, fish sauce, finely shredded kaffir lime leaves, a little finely minced chilli, salt, white pepper and other seasonings. Mix in some beaten egg then steam the mixture in small bowls. Drizzle with a little coconut cream before serving.