This refreshing drink, which gets its tang from passion fruit juice and lemon juice, comes from John Benevides, the bar manager at SRV in Boston.
In a small pan, heat the turbinado sugar with 1 1/ 3 cups water over medium-high, stirring often, until the water comes to a simmer and the sugar dissolves, about 5 minutes. Add the cinnamon stick, stir again, and remove from heat. Let the cinnamon syrup stand until it cools to room temperature, about 15 minutes. Strain into a lidded jar. (Any leftover syrup will keep in the fridge for up to 2 weeks.)
Add the vermouth, passion fruit juice, lemon juice, 1 1/4 oz. cinnamon syrup, and salt to a cocktail shaker. Add ice and shake until cold, 5 to 10 seconds. Strain into 2 glasses filled with ice. Top each glass with 3 oz. prosecco, a splash of club soda, and 3 dashes of bitters.
All dry vermouth is white, but not all white vermouth is dry. While most sweet vermouth is made with red wine, this recipe calls for a sweet white vermouth.