Start by placing the lime wedges, fresh blackberries, and mint leaves into your Boston shaker. Use a muddler to gently press down and release the juices and oils. Don’t overdo it; you want to extract the flavors without tearing the mint leaves completely.
Pour in the white rum and simple syrup over the muddled mixture. Fill the shaker with ice, then secure the lid and shake it for about 10 seconds. This step chills the mixture and ensures that the syrup blends evenly with the rum.
Pour everything from the shaker directly into a highball glass without straining. This keeps the fruit pieces and mint inside, giving the mojito its rustic charm. Top it up with the club soda to add fizz and lighten the flavors.
Use a bar spoon to give the drink a gentle stir, mixing the soda with the muddled base. Finally, garnish with a fresh mint sprig. For extra aroma, lightly slap the mint between your palms before adding it to the glass—it releases natural oils and enhances the fragrance.