Also spelled asafoetida. Otherwise known as 'stinking gum' and 'devil's dung' in English, and as 'hing' in Bengali, Gujrati, and Hindi.
Asafetida is a resin obtained by drying the milk from the root of Ferula asafoetida and other plants of the genus Ferula, which is part of the parsley family (Apiaceae). The pure resin is light brown in color.
The name asafetida is derived from a latinized form of the Farsi word 'aza', meaning 'resin', and from the Latin word 'foetidus', meaning 'smelling' or 'fetid'.
As is probably already clear, asafetida absolutely stinks. It has a breath-takingly rank odor that I am at a loss to adequately describe. Slightly sulphurous, vaguely reminiscent of dirt, or of something rotting, and yes, there's a sort of shit-smelling undertone. If you ever get to smell pure asafetida, the very last thing you will want to do is eat it.
And yet not only is it added to food, it is also considered a delicate and valuable spice, and quite rightly so in my opinion. When a tiny amount of asafetida is added to hot oil and lightly fried for a few seconds, the smell and taste of it changes utterly. I have heard it said that it can be used as an alternative to onion and garlic in Indian food, and indeed Brahmins in India who do not eat garlic use asafetida in its place. Personally though, I have to say that the taste bears only a passing resemblance to onion or garlic. It adds instead an intriguing bitter-sweet, slightly earthy tang, which adds richness and depth to many dishes and complements the flavors of many other Indian spices.
Asafetida is available commercially in two forms: as pure resin (in lumps or powdered) and in a diluted powder form, which is actually a mixture of resin and corn flour, often with salt and some coloring added too. I do not really recommend the diluted kind, although many people do use it. If you ever get the chance to buy pure asafetida though, give it a try. Inevitably you will smell it, and after you do so you will have to be very brave indeed to use it in your food; but if you are cautious and sparing with it and fry it properly you will be very pleasantly surprised.