1. Under cold running water, peel off and discard the lacy outer membrane of the squid. Pat the squid dry with paper towels, slice in half lengthwise without cutting completely apart, and spread open, butterfly fashion.
2. Cut the squid lengthwise into 1/8-inch-wide strips. Over high heat, bring 2 cups of water to a boil in a small saucepan. Add the strips of squid and return the water to a boil. Drain at once, rinse in cold running water, and set the squid aside.
3. If you are substituting clams, save the juice. If there is less than a cup, augment it with bottled clam juice. Strain the clam juice through a fine sieve into a small saucepan and bring it to a boil over high heat.
4. Add the clams, return to a boil, then immediately drain and set them aside to cool. Slice the clams into narrow strips.
5. In a small saucepan, bring 2 cups of water and the salt to a boil. Blanch the scallions by dropping them into the water and boiling for 1 minute. Drain at once and run cold water over them to cool them quickly.
7. Add the scallions and squid (or clams) to the miso dressing and stir gently until the ingredients are thoroughly coated. Serve at room temperature in small bowls, as a first course or as part of a Japanese meal.
