Combine all ingredients in a cocktail shaker filled with ice cubes and shake to chill thoroughly.
Place the vanilla sugar in a shallow bowl or small plate. Moisten the rim of the glass with a little of the cocktail mixture or water and dip the moistened rim into the sugar to coat the edge. Strain the cocktail into the glass.
Using a sharp paring knife, cut the bean lengthwise, leaving it attached on 1 end, so that it can sit on top of the glass rim. Serve chilled.
Recipe courtesy Emeril Lagasse