The cordyceps is as fascinating as it is gruesome: it sounds like the stuff of a Hollywood horror film, where a hot and hunky hero (with an ultra-glamorous heroine at his side) saves humankind from a zombie apocalypse. Fortunately, the fungus that creates cordyceps hasn't spread to humans (and let's hope it doesn't), but it does attack myriad insect hosts.
It's made when a parasitic fungus invades an insect, turning it into one of the living dead, with no mind of its own, and impelling it to climb to a high point on a plant. Overtaken by fungal spores, the insect dies, and a type of mushroom grows out of its head. The spores then fall onto the ground or are dispersed by the breeze, going on to infect more insects.
Of course, somebody, somewhere in China figured out long ago that this grisly fungus was edible. In traditional Chinese medicine, cordyceps are said to be a warming ingredient that increases energy and libido, is good for the blood and alleviates aches, pains and depression. There are many types of cordyceps, and not all of them are eaten - the Ophiocordyceps sinensis used in Chinese cuisine comes from the larvae of the ghost moth, and it does resemble its host.
Cordyceps have a mild taste and are usually used in savoury dishes. For an energising tea, mix cordyceps with chrysanthemum leaves and ginseng, then simmer with water and rock sugar. This should be consumed in small quantities. You can also make soup by cooking chicken with cordyceps, along with water, and salt to taste, for several hours.