Muddle 5-10 blueberries in agave syrup. Combine ingredients in shaker and shake and strain on ice in a tumbler. Garnish with mint sprig.
The original recommends a dry shake of ingredients and straining it in glass filled with pebble ice.
The Bluebeard cocktail is based on the Blackbeard (in PDT cocktail book) made with blackberries in the place of blueberries and lime in place of lemon juice. The original was created by Daniel Eun.
PDT cocktail book