Add the fresh blackberries and 1 sprig of fresh rosemary to a glass, and then muddle using a cocktail muddler.
Add the blue curaçao, grenadine, and vanilla vodka to the glass, and then mix with the muddled blackberries and rosemary.
Add a handful of ice to the glass, and then top up the glass with chilled soda water. Garnish with a sprig of fresh rosemary and a few more blackberries. Light the rosemary just before serving, for a smokey herbal finish.