This takes me back to days of my childhood, sitting in the cherry tree in my back yard reading books. My grandma would make cherry jam for us if we picked all the cherries l. It's one of my all time favorites. Not only is it good on toast, I love mixing it with a little Dijon mustard for a glaze on grilled pork loin.
6 cups sour cherries, pitted
2 cups chopped rhubarb
5 tablespoons lemon juice
1 2/3 cups water or juice from cherries
6 tablespoons low sugar pectin
2 1/3 cups sugar
1 tablespoon butter
10 - 8oz. Canning jars with lids and rings
Place the cherries and the rhubarb in a blender with the lemon juice and water and blend until smooth. Place the mixture into a large pan over high heat.
Sprinkle the pectin over the cherry mixture one tablespoon at a time and stir to combine. Bring to a rolling boil that can't be stirred down.
Add the sugar and salt and bring back to a to a rolling boil. Add the butter. Boil for for one minute stirring constantly. Remove from heat.
Fill your jars with the jam leaving 1/4 inch head space. Skim off any foam with a teaspoon. Wipe the rims off with a damp paper towel.
Seal the jars with the prepared lids and seals.
Process the jars in a prepared water bath for 10 minutes. If you live at a high altitude, process for 20 minutes.
Remove the jars from the water and let cool on a dish towel. Check the seals by pressing your finger in the center of the lid. If it makes noise the jar has not sealed properly and needs to be reprocessed or refrigerated immediately.