Mustard is one of the oldest spices used in the world. It's pungent and spicy on the nose, but that heat can be abated with a little acid. Black mustard seeds are the spiciest and most pungent of the varieties, and are typically used in Indian dishes, including the spice blend panch phoron. The seeds can be quickly fried in oil or ghee until they pop and impart a nutty flavor.