Konbu(kelp) looks like so many dusty strips of dark leather in its dried state. Used primarily for stock making, it imparts an elusive sweetness to the water in which it is cooked. You can keep the kelp you’ve used for making stock, covered in plastic wrap, in the refrigerator 3–4 days, then use to make fish rolls or beans and assorted vegetables. Store dry kelp in its original cellophane bag at room temperature until opening, then transfer remaining pieces to an airtight, dry container. Kelp is rich in calcium and other minerals; caloric count is not available but thought to be low. Hidaka konbu or hidaka dashi konbu from Hokkaido (the northernmost island of the Japanese archipelago) is considered the best.
