Mustard seed, light and dark

The light mustard seed probably comes from the Mediterranean region, but various cultivars are also grown in northern, central and southern Europe. Related species are S. cernua (syn. Brassica cernua) from China and Eruca sativa (syn. Brassica eruca) from Eastern Europe and Central Asia. Cooking mustard is a popular addition to boiled or grilled meat in Western Europe (and the US); it is also very often used in sauces. Since mustard seeds contain emulsifiers, mustard not only improves the taste but also improves the stability of emulsified sauces. Mustard seed is often added to pickles (pickles).