4 lbs. medium-sized beets
3 c. onions, sliced into thin rounds
2 c. sugar
2 cinnamon sticks, broken into 2 pieces each
1 Tbsp. mustard seed
1 tsp. whole allspice
1 tsp. whole cloves
1 tsp. salt
2½ c. apple cider vinegar
1½ c. water
Scrub and rinse beets well. Leave part of stem and do not cut the root from beets. (Doing this avoids losing too much of the beet juice before you are ready to can them.)
Fill large pot with beets and water and bring to boil. Cook beets until fork tender and skin slips off easily. Drain beets and cool enough to handle. Slip skins off beets, remove root and tops; slice beets 1/8" to ¼" thick.
Add onions, sugar, cinnamon stick, mustard seed, allspice, cloves, salt, vinegar and water to a large pot and bring to a boil. Turn heat to low and cook 6 minutes. Add beets and cook until beets are hot. Remove cinnamon sticks.
Pour beets and liquid into the hot sterilized jars. Wipe rims and put lids and rings on the jars snugly.
Process beets 30 minutes in a boiling-water bath canner. Wait at least 2 weeks to open.