Pour Limoncello into a chilled martini glass, champagne flute, or other small glass. Add sparkling wine. Top with a lemon zest strip. Serve immediately.
Scrub 10 lemons with a vegetable brush. Using a vegetable peeler, carefully cut enough of the yellow peel away from the white pith to make 2 cups. (If desired, juice lemons and reserve for another use.)
In a large glass pitcher or bowl combine the 2 cups lemon peel and the vodka. Cover tightly and let stand in a cool, dry place for 10 days, gently swirling the mixture in the pitcher each day. Strain mixture through a fine-mesh sieve; discard lemon peel. Return the lemon-infused vodka to the pitcher.
For syrup, in a medium saucepan combine sugar and water. Bring just to boiling, stirring to dissolve sugar. Cool to room temperature.
Pour syrup into the lemon-infused vodka; stir to combine. Cover and chill overnight. Pour limoncello through a funnel into clean bottles; secure lids. Store in the refrigerator.