In a smallish Collins glass, muddle lime juice with 1/2 to 1 tsp. superfine sugar. Add the mint leaves, mushing them against the side of the glass Fill the glass 2/3 with cracked ice and pour in the rum. Pitch in the squeezed-out lime shell and top off with club soda or seltzer.
- INGREDIENTS: 2 oz. (6 cl) White Rum 1/2 oz. (1 cl) Lime juice (squeezed fresh) 1 tsp. Superfine sugar 3 Mint Leaves Club Soda or Seltzer