Pour the sugar in a saucer. Cut the lemon in half and squeeze out the juice. Rub the rim of a cocktail glass with a lemon half and dip in sugar to coat the rim.
In a cocktail shaker combine gin, triple sec, lemon juice, vanilla and fill it up with ice. Shake until the cocktail shaker is too cold to hold.
Pour in the cocktail glass and decorate with a lemon slice. Use golden sugar stir stick if desired.