1. Place water,rhubarb, apples, and sugar in a large saucepan. Cover and simmer until fruit is soft, about 30-40 minutes, stirring occasionally. Stir in cinnamon. The applesauce will be chunky. If you prefer smooth applesauce, you can run it through a blender or food processor. Serve at room temperature or cold. Store rhubarb applesauce in refrigerator for 2-3 weeks. This applesauce also freezes well, store in an air-tight container in the freezer for up to one year.