Hijiki seaweed is green to brown with many narrow leaves when fresh. After harvesting, the seaweed is cooked and dried, and the seaweed turns black. Hijiki has a nutty flavor with soft notes of licorice and a firm bite. Soak the dried seaweed briefly in lukewarm water before preparation, then the seaweed can be simmered, stir-fried, or steamed. Simmer the seaweed in, for example, soy sauce.