All about nori, the sheets of laver (seaweed) like dark green paper used to make sushi rolls and sometimes used to tie toppings to nigiri sushi
Nori (海苔) is commonly used to refer to pressed sheets of dried laver used in sushi bars to make sushi rolls. The original Nori was a paste, and a form of it is still popular in Japan, but today the term is commonly used to refer only to the dark green paper-thin sheets used in sushi bars.
Shredded varieties and mixtures containing other flavoring are also popular ways to eat nori in Japanese cuisine, but again most westerners know only the sheets of nori used in their local sushi bar or Japanese restaurant.
Nori as we see it is pressed, dried sheets of seaweed. This seaweed is a type of red algae, although by the time it's dried and ready to eat it's dark green; almost black in color. Korea and Japan both produce billions of sheets of Nori each year, but increasingly cheaper grades are being supplied by China. Every year the demand in America for nori to make various sushi rolls increases, even though nigirizushi remains the staple of the Japanese sushi experience.
Nori production was always unpredictable, as fishermen gathered it off rocks just offshore, and eventually off fencing and netting kept at around 25 feet below the surface. After harvesting the seaweed is washed, shredded and pressed to make giant sheets. It is then roasted, which changes the color to a darker green or even black, then it's cut into small squares ready to be packaged or eaten.
Only in the last generation or so have sushi rolls become the top sellers in the world of sushi. As nori harvesting became predictable and steady, and as non-traditional sushi rolls flourished in America, nori gained prominence in the arsenal of the sushi chefs. Before the 17th century, laver was gathered in an ad hoc fashion and was a rarity. Then in Japan people began to cultivate it, and today the manufacturing process is mature and predictable.
Nori is used in several ways in sushi bars, for nigiri "bands" holding toppings in place, for the wrapping around gunkanmaki, for temaki (hand rolls) and most sushi rolls. No need to use it sparingly either, because nori is loaded with minerals like magnesium, zinc, iodine and potassium. And nori is not lacking in vitamins like vitamin A, vitamin B complex, and vitamin C. Nori is high in fiber and low in carbs and fat. Nori is rich in calcium and iron and scientists suspect it has many other health benefits.