Kaffir limes

Sometimes now called a makrut lime, this fruit and its scented leaves comes from a different tree to regular limes. The kaffir lime has similar colours to a lime but with a knobbled, bumpy skin and an amazing fragrance. Sadly, it is hard to buy in the West, but if you can grow or get it, use sparingly as the juice is sour and bitter (prized as such) and the zest intensely aromatic. (See for lime leaves.)