Combine all of the liquid from canned beets (reserving the beets), apple cider vinegar, sugar, peppercorns, and pickling spice in a medium-sized saucepan. Bring everything to a slow simmer for 5 minutes, whisking occasionally to combine. Remove the saucepan from the heat and allow it to cool.
Once the liquid is cool enough to handle, add approximately half of the reserved sliced beets, sliced red onion, and peeled hard boiled eggs.
Transfer the entire mixture to a large container and refrigerate for at least 24 hours or up to 7 days.
Cook the hard boiled eggs using whatever method you like. However, if you have an electric pressure cooker, the method detailed in my recipe for Classic Deviled Eggs is particularly easy.