- Pour wine into 3 ice cube trays and freeze until solid, at least 4 hours or overnight.
- In a medium saucepan combine sweetener, water, and blackberries. Bring to a simmer over medium heat, stirring to dissolve sweetener. Simmer for 5 minutes, occasionally mashing the berries against the side of the pan. Strain well and chill completely.
- To a blender add wine ice cubes and ¾ cup berry syrup. Blend until smooth.
- Pour slush into glasses and garnish with blackberries and lime wheels.
- Keep remaining syrup in an airtight container in the refrigerator.
Note: Berry syrup will separate as it chills. This is normal. Simply shake well right before using.