Playing hard to get Precisely when and how humans discovered that the stigma of the Crocus sativus blossom is not just edible, but deemed to be of such culinary and medical importance that it's worth the tedious labour of its picking and processing, is lost to antiquity. But there's no doubt that saffron has an extremely long history in many cultures, such as those in India, the Middle East and parts of southern Europe.

Saffron is by far the world's most valuable spice: it sells on the wholesale market for about HK$40,000 per kilo, although the price varies greatly depending on quality and provenance. As with many valuable products, it often falls victim to counterfeiters. A friend once brought me some saffron back from Morocco: well, it looked like saffron, but the scent was very faint, and when infused in warm water, the colour that leached from the threads was different - less vivid yellow - than the colour I know comes from real saffron.

The saffron harvest takes place between late October and early November, depending on the weather in the countries - including Spain, Italy, Iran, Morocco and India - where it is produced. Its cultivation is tedious - the plant is grown from a bulb-like corm because it's not self-propagating - and its harvesting is labour intensive. Each flower has to be picked at precisely the right time (before it opens), and each one yields just three stigma, which need to be dried under precise conditions.

Saffron is sold whole (as threads) or ground. It's much better to buy whole because the ground stuff is easier to adulterate. The flavour is released when the threads are soaked in hot liquid or fat.

The distinctive, bitter saffron flavour complements many ingredients: it's delicious in cream-based sauces, seafood dishes and when cooked with poultry or rice. A little saffron goes a long way - you need just a pinch of it in a dish: if you add too much, the taste will be bitter.