In shaker, combine 2 wedges of lemon, 6 basil leaves basil, half a teaspoon of superfine sugar, and a dash of ground ginger. With muddler, mash ingredients until basil is bruised and lemon releases its juices. Stir in pineapple juice and gin. Pour mixture into Collins glass filled with ice, discarding lemon wedges. Top off with seltzer. Garnish with additional basil, if desired.