If you have access to a food processor, mince the cranberries and rhubarb to a fine pulp or use an immersion blender or food chopper to coarsely chop the cranberries and rhubarb and leave some cranberries whole, if desired. Put cranberries and rhubarb in a large glass jar. Add sugar, vodka and water. Stir. Cover tightly and set in a dark place at room temperature for at least 3 to 6 months.

Before serving, strain through double thickness of cheesecloth. Discard fruit.

Store cordial in a jar or decorative glass bottles with a tight fitting cap.