1 cup apple cider vinegar (or white wine vinegar)
1 cup water
1/4 cup granulated sugar or maple syrup (or substitute with 2-3 tablespoons stevia/monk fruit sweetener equivalent)
1 teaspoon salt
1/2 teaspoon whole peppercorns
4-5 whole cloves
1 small cinnamon stick (optional, but adds depth)
1/2 medium red onion, thinly sliced (optional, for flavor)

Instructions
Cook the Beets: Place the whole, unpeeled beets in a large pot and cover them with water. Bring to a boil, then reduce heat and simmer until the beets are fork-tender (30–45 minutes, depending on size).
Peel and Slice: Drain the hot water and rinse the beets with cold water. When cool enough to handle, the skins should slip off easily (use a paper towel to avoid staining your hands). Slice the beets into 1/4-inch thick rounds, wedges, or dice them. Divide the prepared beets among two clean pint-sized jars.
Prepare the Brine: In a small saucepan, combine the apple cider vinegar, 1 cup of water, sugar (or sweetener), salt, peppercorns, cloves, and cinnamon stick (if using).