Divide cherries between two 1 pint clean, dry canning jars.
To each jar, add a sprig of thyme and 6 peppercorns.
Put balsamic vinegar into a saucepan over medium-high until boiling.
Remove from heat and divide the hot vinegar between the two jars of cherries. The vinegar should cover the cherries, but if not, add some more vinegar to the pot and simmer until you have enough. Seal jars, allow to cool and then refrigerate for 2-3 days before using.
Notes
the time indicated for this recipe does not include pitting the cherries.