Nigella seeds have a mild nutty, onion flavor and they are used as a condiment in India and the Middle East on flatbreads and vegetable dishes. Their shape has an interesting appeal, more edgy than sesame, but they can be used in many of the same ways. Give them a quick toast in a dry skillet to bring out the most flavor.
In India they are known as kalonji and in the United States they are called charnushka. They are also frequently (and mistakenly) called black onion seeds, black cumin and black caraway.
Nigella seeds are hard and crunchy with a flavour like toasted onions. They are dry roasted in India and used on flatbreads like naan and they are particularly good with potatoes and root vegetables. They are also one of the five spices that make up panch poran, a spice mixture from Bengal.