In a large bowl combine the cranberry and orange juice. Transfer the juice to a freezer safe bag and freeze until firm, about 4 hours. (See notes).
Remove from the freezer. Break up the frozen juice and place in a large pitcher or punch bowl. Use a wooden spoon to carefully break up the frozen chunks into smaller pieces (should get sort of slushy when you do this).
Add the soda and stir to combine.
Add in the cranberries and orange slices and serve cold.
Notes
You don't have to freeze the juice. I love a slushy drink so I always freeze mine. If you're in a time crunch or just don't want to freeze it, then just skip that step.Recipe from my mother-in-law.