Nigella

nigella sativa, often known as nigella, onion seed, kalonji (often referring to the oil), and sometimes as black cumin, fennel-flower, nutmeg-flower, and a few others.

The onion-seed name leads to some confusion, since this is not the seed of onions, but to seeds tasting like onions. The plant is unrelated to the onion family

The taste resembles a mix of onions, black pepper and oregano. Or, if old, mostly bitter :)

Used e.g. in indian and middle-eastern cuisines, e.g. in bread, fish, salads