Hijiki is a popular seaweed in Japan, particularly with the "health-conscious" consumers. The almost black seaweed is a "twiggy" looking black marine algae that contains high amounts of vitamins, minerals, fiber, and calcium. Hijiki is sold cooked and dried and is available in Asian food stores. The product is produced in Japan and Korea.
Traditional culinary uses include frying the hijiki in a shoyu sauce with vegetables. It may also be used as a garnish on sushi or onigiri, or in a simple cucumber salad.
Hijiki is a tough seaweed and should be soaked in lukewarm water for about 15-20 minutes until soft. The plant will expand approximately 7 -10 times its dried size. It may be fried in a small amount of oil then simmered with soy sauce and vegetables. It can also be fried and simmered in a dashi soup.
If you can't find hijiki you can substitute equal amounts of: