This jam doesn't use any pectins or gelatins, just rhubarb, sugar, beets, and plain old water. It comes out a deep red with an earthy quality from the beets and a hint of tartness from the rhubarb. Pair it with goat cheese and walnuts.
In a large bowl, combine the rhubarb with 1 cup of sugar.
Mix well and let sit for about 30 minutes until some juice forms in the bottom of the bowl.
In the meantime, cook the beets with the remaining sugar and water in a medium pot over medium high until tender, about 45 minutes; stir occasionally.
Add rhubarb mixture including juices and stir.
Cook, while stirring, 18 to 20 minutes until rhubarb are very soft.
Process the beets through a potato ricer or large strainer and return to the pot.
Taste for sweetness and add sugar, if needed; cook a few minutes to dissolve any added sugar (the jam's flavor will mellow as it cools).
While jam is still hot, ladle into hot sterilzed canning jars, leaving 1/4 inch head space at the top; remove air pockets by running a long, non-metallic utensil or skewer between the jar and the jam.
Top with new, clean lids, close tightly and let cool to room temperature.
Once cooled, test the seal; if the lid springs up when you press your finger into the center - it is not sealed.
Process any that have not sealed for 15 minutes in a hot water bath, then test the seal again.
NOTE: To sterilize jars, fill a large pot with water and bring to a boil over high heat. Reduce heat until barely bubbling. Immerse three 8 ounce jars and leave there while you are cooking the jam. Place lids and rings in a small saucepan covered with hot water.