Indian Methods for Toasting Spices
Toasting heightens the flavor of spices by releasing their volatile aromatic oils, whether you toast with dry heat or in fat. Indian cooks almost never use spices without toasting them first. Sometimes the spices are toasted dry in a skillet until they darken and become fragrant, then they're cooled and ground to a powder. For dishes where the spices are left whole, they are often "popped," or bloomed, in hot oil or ghee (clarified butter).
The popping technique is used with whole spices such as cumin seed and mustard seed. Heat the fat in a skillet until very hot. Add the spices, shielding your face with a pot lid or spatter screen. Let the spices pop and darken (but not blacken) before adding the next ingredients.