1In small bowl, stir together 2 tablespoons sugar and 1/2 teaspoon finely gingerroot. Place mixture on small flat plate. Rub fresh gingerroot slice around rims of 2 martini glasses to moisten. Dip moistened rims of glasses in ginger sugar mixture.
2In 1-quart saucepan, heat ginger simple syrup ingredients over low heat until sugar is dissolved. Let stand 15 minutes. Use within 2 days.
3Fill martini shaker with ice. Add gin, pomegranate juice, and 1 oz of the ginger simple syrup; place lid on shaker, and shake until cold and blended. Pour into prepared martini glasses; add prosecco.
4Garnish with pomegranate seeds.