Kaffir lime leaves originate from Southeast Asia, and bring a delightful, aromatic and fresh flavour to dishes which contain them. A staple seasoning in Thailand, they are used to bring an acid balance to the fierce chilli heat which Thai food often contains. The flavour of kaffir lime leaves is earthier and sweeter than standard lime juice or zest, but with the same citrus base. The leaves can either be added whole, or crushed in the hand to release the oils contained within. They need to be stored in a cool, dark place (a pantry is perfect!) to prevent them losing their colour.