Prepare the dressing: Whisk the vinegar, lemon juice, salt, and sugar together in a bowl until the crystals dissolve. Add the ginger, soy sauce, and sesame oil, whisking to incorporate.
When ready to serve, toss the seaweed with most of the dressing and half of the sesame seeds. Taste and add more dressing to suit your taste. Divide among six small salad bowls, sprinkle each portion of seaweed with the remaining sesame seeds, and serve immediately.
Cook's Note: I am crazy about green (ao) tosaka seaweed, prepared by the Kaneryo company, exported from Tokyo by the Central Trading Company. It is heavily salted, packed in a plastic bag, and sent to the U.S. frozen. I buy mine at the great Japanese store Katagiri in New York City, where it's on the refrigerator shelf already defrosted. If you buy it, you can store it, defrosted, in your refrigerator for a couple of weeks.
From David Rosengarten Entertains: Fabulous Parties for Food Lovers by David Rosengarten (John Wiley & Sons, 2004). © 2004 by David Rosengarten. All rights reserved.
David Rosengarten is a food writer, cookbook author and cooking teacher. He is the editor-in-chief of The Rosengarten Report, a James Beard award-winning newsletter. He is the author of several cookbooks, including It's All American Food, which won a James Beard award for Best American Cookbook. He has hosted or co-hosted more than 2,000 television shows, including "Taste," which won a James Beard award for Best National TV Cooking Show. Previously he served as a contributing editor for Gourmet.