Except for sushi nori, which comes pretoasted, just before using, nori should be lightly toasted by briefly passing the unfolded sheet over a gas flame or electric burner. The nori is ready when the color changes to a more brilliant green and it becomes crisp and fragrant. (Be careful when toasting - nori is delicate and burns easily.)
Nori is most commonly used to wrap around rice balls, which are probably the most common and popular addition to Japanese lunch boxes and picnic baskets. Nori is also used to wrap other foods, such as Nori-Maki. Cut into 2-inch strips, nori is delicious when wrapped around mouthfuls of warm rice dabbed with umeboshi paste. Crumbled or cut into strips, nori can be used to garnish soups, vegetables, and grain or noodle dishes.
Recently nori is being used as a party food in a variation of nori-maki called te-maki. Te-maki literally means "wrapping by hand." A quarter sheet of toasted nori is topped with a little sushi rice or noodles along with an assortment of foods such as raw tuna, avocado, or raw vegetables. Condiments such as umeboshi or wasabi may be added, then the nori "package" is rolled into a funnel or cone shape. Te-maki adds an exotic flair to parties, especially when served with hot sake.
Another variety of nori, called ao nori, or green nori, is sold in flake form. Ao nori is used as a garnish or as a seasoning in fried rice. This type of nori is the richest in iron and protein.