, about 2 large lemons
chilled sweet sparkling
, such as Asti Spumante
CHILL 4 large martini glasses in freezer. Combine sugar with lemon juice in a small bowl, whisking until sugar dissolves. (Lemon syrup can be made 3 days ahead and kept refrigerated. )
COMBINE 1/4 cup lemon syrup and vodka in a martini shaker. Add ice cubes. Cover and shake 8 to 10 times, then strain mixture into prepared glasses (about 3 tbsp each). Add 1/4 cup chilled sparkling wine to each glass. Garnish with lemon slices and serve very cold.