1-2tablespoonsagave nectar or other sweetener like simple syrupadjust as needed - we liked it without!
Add wine, nectarines, mixed berries, Grand Marnier, and sweetener (if using) to a blender and puree until smooth.
Work in batches to add the ice to the sangria mix. Pour out 1/2 half of the mixture into a separate container and add 3 cups of ice. Blend until smooth. Pour into a pitcher and repeat with the second half of the fruit mixture and the rest of the ice (3 cups).
To serve, rim glasses with sugar and pour frozen sangria into glass. Garnish with additional berries and nectarines.