Ingredients One 1-liter oak barrel (see Note) 22 ounces gin 11 ounces dry vermouth Ice Lemon twists, for serving Instructions If the barrel is new and dry inside, fill it with water and let stand until watertight, about 24 hours. Drain. Using a funnel, fill the barrel with all of the liquid ingredients. Let age, tasting a sample once a week, until the cocktail has taken on a rounded but not overly oaky flavor, about 1 month. Strain the cocktail through a coffee filter–lined funnel into a glass container and store indefinitely. To serve, pour 3 ounces into an ice-filled cocktail shaker and stir until chilled. Strain the drink into a chilled cocktail glass. Garnish with a twist.