Dry roasting or dry-frying in culinary terms usually applies to a preparation method for whole spices. The whole spices are heated in a small dry frying pan, wok or tava without any oil until they start to colour and release their essential oils. This tends to revive dries spices. They are left to cool and then ground to a powder in a mortar and pestle or electric coffee grinder. Nothing is gained by dry roasting powdered spices.