4 to 6ouncesblackberry soda water or plain soda water
Build the cocktail in a heavy bottom cocktail glass, like a collins glass or old fashioned glass. Add the sugar, mint, and blackberries. Muddle the 3 ingredients together, slightly juicing the blackberries and "bruising" the mint to release the flavor. Try not to mash it into a million pieces.
Top the muddled ingredients with rum. Fill the glass with ice - preferably crushed.
Top with blackberry infused soda water or traditional club soda. Garnish with a large mint sprig and extra blackberries.
To make this a refreshing mocktail, just leave out the rum and make it according to the instructions.
Make your own crushed ice by smashing regular ice cubes in a zip bag with a mallet.
The amount of soda water may vary depending on how many ounces your glassware holds.