"Cucumber vodka, elderflower liqueur, Sauvignon Blanc, limeade, minted rosemary syrup, and a few drops of rosewater add up to a fragrant and refreshing summer cocktail. Garnish with thin cucumber slices. It's a signature cocktail at the Peninsula in Chicago."
Combine water, sugar, mint, rosemary, and lemon zest together in a saucepan; bring to a boil, remove from heat, and let steep for at least 10 minutes. Strain through a fine-mesh sieve into a glass jar, cool to room temperature, and chill syrup in the refrigerator until cold, at least 30 minutes.
Combine vodka, elderflower liqueur, white wine, limeade, and 1 fluid ounce chilled mint-rosemary syrup in a cocktail shaker. Fill the shaker with ice, cover, and shake until chilled. Strain cocktail into a martini glass and garnish with cucumber and rosewater.