Stir in the kirsch (if using!) and pour the liquid back over the cherries, shimmy the bowl gently again, cover tightly again with plastic wrap, and let stand at room temperature for 3 days. After three days, drain the liquid from the cherries into a saucepan again and bring to a boil. While the liquid is heating and coming up to a boil, use clean hands to transfer the cherries gently from the bowl to sterile canning jars. Lay a lid over the jars to keep fruit flies out. After the liquid comes to a boil, remove from the heat, put a lid in place, and let it cool completely to room temperature. When it has cooled, lift the lids from your jars and pour the pickling liquid over the jars to cover the cherries. There is a good chance you will have extra pickling liquid left. Pour that into a sterile jar, too! Wipe the rims with a paper towel dipped in vinegar, then fix the two-piece, non-reactive lids in place. Screw the rings on until fingertip tight, label the jars, and store in a cool, dark place for at least 1 month before eating, but up to a year!