Before Daylight
Ingredients
Method
Bring 6 oz. fresh or frozen blackberries and ¼ cup water to a boil in a medium saucepan over medium heat. Cook, stirring and mashing berries with a potato masher or fork, until soft and pulpy, about 5 minutes. Add 1 cup sugar and cook, stirring often, until dissolved, about 3 minutes. Let cool. Do Ahead: Blackberry syrup can be made 1 week ahead. Transfer to an airtight container; cover and chill.
To make 1 cocktail, combine one quarter of one 4" piece ginger, peeled, thinly sliced, 1¼ oz. mezcal, 1¼ oz. sweet vermouth, 1 oz. fresh lime juice, and 1 oz. blackberry syrup in a cocktail shaker. Fill shaker with ice, cover, and shake vigorously until outside of shaker is very cold, about 30 seconds.
Fill a tall glass two thirds full with crushed ice; pour in 2 oz. ginger ale. Strain cocktail into glass. Garnish with a fresh or frozen blackberry.