GIN & TONIC Fill the glass with ice and swirl to chill the glass. Discard the remaining water. To boost the flavor of the cocktail, add a few lightly crushed juniper berries so they release their unmistakable aroma. Pour in the gin and top up the glass with tonic while stirring gently with a spoon. Adorn the rim of the glass with a wedge of lemon or lime to give the cocktail an added citrus twist.