01 - In a cocktail shaker or large mixing glass, gently muddle the fresh raspberries and cranberries until well crushed and their juices are released.
02 - Add the 100% cranberry juice, raspberry juice, 1 to 2 tablespoons of simple syrup (starting with 1 tablespoon), and freshly squeezed lime juice to the shaker. Stir or shake vigorously to thoroughly combine the ingredients.
03 - Fill two serving glasses with ice. Strain the mixture evenly into the glasses, distributing the fruit pulp as desired for visual appeal and texture.
04 - Top each glass with chilled sparkling water or club soda. Stir gently to integrate the sparkling component.
05 - Taste the mocktail and adjust the sweetness level if necessary by adding more simple syrup.
06 - Garnish each glass with extra berries, a lime wheel, and a fresh mint sprig, if desired. Serve immediately for optimal refreshment.