Many dried and packaged seaweeds are now available in Oriental markets or health food stores. The dried seaweed should be rinsed to remove excess salt before it is soaked.
A rule of thumb is that about one-third ounce of dried seaweed will make about 1 cup of rehydrated seaweed. This varies; you will just have to try a small amount and see. It just takes about 10 minutes of soaking to find out what you have. There is often a stunning expansion. If you soak more than you need, it will keep covered in the refrigerator for about a week, either drained or still soaking. The soaking liquid should not be thrown away. It can be used in soup stocks, rice or grain dishes, or even for watering the houseplants.
A list of available seaweeds:
Dulse (palmaria palmata): A red algae found and marketed all over the world, dulse is the most popular seaweed sold in health food stores. Very high in protein and Vitamin A, it also has the heaviest concentration of iron of any food source. With a salty, nut-like taste, this has long been a popular snack and can be eaten as is, or toasted until crisp.
Wakame (edible kelp, alaria esenta): Black and stringy-looking when dried, it immediately rehydrates in water into long, deep green satiny fronds, a slick spinach-like product with a pleasant mild flavor. It can be chopped for salads and is a must in miso soups. It is harvested mostly in Japan, but there is a growing cottage industry off the shore of Maine. There are even "alaria" clubs in Massachusetts and Maine, groups that go out at low tide to gather the annual seaweed at its peak season from late summer to late fall. High in vitamins C and B12, it also is high in iodine and bromine. It has sugar, starch, calcium, nitrogen, boron, radium, rubidium, cadmium, cobalt and nickel.
Kombu (naga-kombu, laminaria longissima): With long, ribbon-like ruffled fronds, this is another of the kelps and the traditional seasoning in dashi, the fish soup stock that flavors much Japanese food. It has three times the B vitamins of milk and grains, according to Vegetarian Times. It is a flavor-enhancer containing natural sodium glutamate.
Arame (iseniaicyclis): Another kelp, this is black when dried, rehydrates into long, dark yellow-brown strands. It is added to soups or mixed with soybean sauce. With a high concentration of protein, vitamins A, B1 and B2, calcium and potassium, this sea vegetable can be added to soups and vegetables dishes.
Hijiki (hizikia fusiforme): These thin, black, stick-like branches have a strong, rich, almost meaty flavor and a crisp texture. Again, very high in protein, but especially rich in calcium, with an average serving of 50 grams providing 1,000 times as much calcium as a glass of milk. This is prized in China, Japan and Korea as a fresh vegetable and often is combined with rice.
Nori (laver, porphyra tenera): Known here as the sushi-wrapper, this seaweed has an incredible concentration of Vitamin A -- 11,000 international units per 100 grams. It is also extremely high on the charts in protein and has other vitamins and minerals. The product marketed here is sun dried and packaged in sheets of 10. Highest quality are relatively thick purple sheets with a pleasant nut-like smell. Lower quality are thin and green. It is toasted quickly over a flame to bring up the flavor. Laver is harvested fresh for salads in England. The Irish eat it with potatoes, and the Welsh like it with mutton.
Kanten (Agar): This is a dried gel made from red seaweeds and used similarly to hoof and cartilage animal gels. Sold in powdered form or in long icicle-like dried strands, algal gels can do what animal gels do, but more. They set at room temperature in a matter of minutes. Agar can be blended with fruit juices to make an all-natural low-calorie gelatin dessert with a rich supply of vitamins and minerals.