Limes are the major citrus fruit grown in the tropics and are an enlivener for many dishes. The small, yellowy-green key lime is the most common variety with its sour, fragrant juice. Greener Persian limes can be used interchangeably. Both have the remarkable ability to lift flavours in a complex curry or broth. Use the zest for extra fragrance, the juice for tartness and don’t add when the food is too hot as this will kill much of the delightful sourness. Kalamansi limes with their extremely sour and citrussy orange pulp are also used in juices and cooking.