Brassica juncea
Mustard is a condiment made from the seeds of a mustard plant (white or yellow mustard, "Sinapis hirta"; brown or Indian mustard, "Brassica juncea"; or black mustard, "B. nigra"). The whole, ground, cracked, or bruised mustard seeds are mixed with water, salt, lemon juice, or other liquids, and sometimes other flavorings and spices, to create a paste or sauce ranging in color from bright yellow to dark brown.