Place mint leaves, whiskey, sugar, ice and the juice of 1/2 lime into a cocktail shaker. Shake it like you mean it! Add 2 more lime wedges and the sugar, and muddle again to release the lime juice. Do not strain the mixture.

Fill a glass almost to the top with ice. Pour the lime mixture over the ice, and top the glass with club soda. Stir, taste, and add more sugar if desired. Garnish with lime wedges or mint.