Lime, rum, and allll the leafy green herbs. Cheers to that!
In a cocktail shaker, using a muddler or the handle of a wooden spoon, muddle the herbs, sugar, and ginger until coarsely mashed. Add the rum and the lime zest and juice. Fill the shaker with ice. Cover and shake vigorously.
Divide between 2 glasses filled with ice. Top with the seltzer. Garnish with the herb sprigs.