Inspect the chokecherries and see if they need to be cleaned or not. If they’re dirty at all, immerse them in tepid water, remove with a slotted spoon to a bowl to dry, and reserve.
In a non-reactive pot, combine the chokecherries, vinegar and water. Bring the pot to a boil, then remove from heat. Mash the berries well with a potato masher or other tool-the more you mash them, the better the syrup will be. Mashing after cooking makes easier to crush, and reduces splattering.
Strain the mixture into a towel or thick cheesecloth over a colander. Cool until you can handle it, then wring out the chokecherry juice. Save or freeze the pits and bits of skin to make fruit scrap vinegar.
Measure the juice and combine with an equal volume of sugar in a wide pot and bring to a boil. Boil it until it barely coats the back of a spoon, about 5-10 minutes.
Pour the mixture into half pint or pint canning jars and cook in a water bath for 5 minutes or 10 minutes for pints. Chokecherry syrup can also be frozen and will last for years.
Video
Notes
With very small varieties of cherry like pin cherries, the mixture may gel from the pectin, warm it and it will loosen.
Variations
A friend from MN recommends putting the cherries through a meat grinder to release more of the almond flavor. It's excellent.
You can add ginger, lemon or orange zest while extracting the juice from the fruit for different flavors.
I like to use homemade wild cherry vinegar, but just about any vinegar will work fine.