The Blackthorn is a sloe gin-based cocktail that emerged in the early 20th century. The blackthorn is the name for Prunus spinosa, the plant whose fruit is called sloes. Those fruits are infused in gin to create sloe gin, from where the cocktail name. The name Blackthorn was assigned to many cocktails, all of which are using sloe gin as their base.
The cocktail is tasty and intriguing, with sweet, savory, and spicy hints of cloves and cinnamon.
Fill a shaker with ice and add the sloe gin, vermouth, and bitters.
Stir well until very cold.
Strain into a chilled cocktail glass.