Asafetida or asafetida is the dried latex (oleo-gum-resin) exuded from the living rhizome, rootstock or taproot of an umbelliferous plant of varied species. This dried gum resin and has a unique odor from its sulfur compounds that are present in it. It resembles the flavor of shallot or garlic and is used many times as a substitute. It is available in lumps or powdered form. Powerful flavor use sparingly. Asafetida should always be fried. No you should not add while the food is being cooked. It needs to be fried in little oil for a few seconds for the resin to dissolve in the fat. A common rule of Pakistan & India n cookery is, if hinge is used in a dish, garlic is not as both have strong flavors.