Divide the peaches and blueberries between 3 pint-sized mason jars.
Make the brine: Put all of the remaining ingredients into a sauce pot over high heat, and boil until the sugar is dissolved.
Use a ladle to divide the coriander seeds, peppercorns, and cinnamon sticks between your jars. If you have an extra cinnamon stick, you can toss it into the compost.
Pour the remaining hot brine over the fruit. Let the jars sit on the counter until they’re cooled enough to handle, then screw on the lids and refrigerate
Refrigerate until you’re ready to eat. You want the fruit to steep for at least an hour in the fridge, but the longer they steep, the deeper the flavor will get. They will keep for 2-3 weeks in the fridge.