I just canned 6 pints this weekend with red onions. I'll get the recipe at home - took a while to find just the right one on the Internet. Basically, cooked beets until tender then sliced, sliced red onions. Layered into jars - onions, beets, onion, and finished with layer of beets and then made a hot canning liquid of 1 1/2 cup wine vinegar, 1 1/4 reserved liquid from beets (I accidentally poured out so used water instead) 1 cup sugar, 1/2 teaspoon salt, 1/2 teaspoon dry mustard and two teaspoons dill seeds. I also added fresh dill flowers since I had them in garden. Processed in water bath for 30 minutes.
OK doing this from memory at work - so if you are interested I'll get exact recipe and post. But thought this would at least give you some idea.
I know what you mean I'm the only one who likes them - so get them all to myself YUM
Sandee