In the Moscow Mule (page 139), the vodka core keeps the cocktail clearly focused on the interplay between ginger, lime juice, and the fizziness of seltzer. If a more flavorful spirit is used, the proportion of ingredients may need to be adjusted—a principle that's clearly illustrated in our version of the Dark and Stormy (which, like the Moscow Mule, was traditionally made with ginger beer). To balance the rich molasses flavor of Gosling's Black Seal rum, we up the amounts of both the ginger syrup and the lime juice.
Pour the seltzer into a Collins glass.
Short shake the remaining ingredients with ice for about 5 seconds, then strain into the glass. Fill the glass with ice cubes and garnish with the lime wheel and candied ginger.