Combine the sliced cucumbers, onions, and kosher salt in a large bowl.
Cover with ice water and let the mixture rest for 2 hours.
Drain thoroughly and rinse lightly under cold water.
In a large saucepan, combine the white vinegar, apple cider vinegar, honey, sugar, mustard seeds, celery seeds, turmeric, and peppercorns.
Bring the brine to a gentle boil, stirring until the honey and sugar dissolve completely.
Add the cucumbers and onions to the hot brine.
Simmer for 5 minutes until the cucumbers are slightly translucent but still crisp.
Carefully transfer the pickles and hot brine into clean, sterilized jars.
Allow the jars to cool completely before sealing.
Refrigerate for at least 24 hours before serving for the best flavor.