Pickled beets, magenta and gold globes suspended in a vinegar based brine, have been a long time favorite of mine. The recipe below is the one I grew up with, with a lower sugar content than many recipes, but the sugar can be reduced even further if desired.
Once pickled, the beets and onions are delicious alongside summer classics like potato salad and something grilled, and they're also a perfect addition to grain salads- my favorite lately has been french green lentils, fresh parsley and thyme, local chevre, the pickled beets and onions, plus a simple olive oil/vinegar dressing. A couple splashes of the pickling brine is a delicious addition.
Once your beets are gone, the remaining brine can be used as the vinegar portion of vinaigrettes, and can also be used to pickle hard boiled eggs.
Approximately 1 quart beets
1 large onion, or two smaller onions, thinly sliced
1.25 cups apple cider vinegar
1.25 cups beet cooking liquid
1/4 cup raw cane sugar (increase to 1/2 cup if desired)
1 teaspoon kosher salt
A few whole peppercorns, if desired
In a large pot, cover beets with a few inches of water, bring to a boil. Cover and continue to cook over medium/high heat until beets are tender when pierced with a fork, adding more water to keep beets covered if needed. Once beets are tender, pull the beets from the cooking water to cool, reserving 1.25 cups cooking water which you'll use as part of the pickling brine. When the beets are cool enough to handle, gently remove the beet skin by rubbing the beets with your hands.
Cut beets into shapes/sizes you like, and place in a glass jar large enough to hold the beets and pickling liquid. I like wide mouth quart jars. Add sliced onions, and peppercorns if using.
In a medium sized pot, combine reserved beet cooking water, vinegar, salt, and sugar. Bring to a boil, remove from heat and stir until sugar and salt have dissolved. Pour hot brine over the beets and onions, cool to room temp, then store in the fridge. These should keep for at least a couple weeks in the fridge as the vinegar and sugar both act as preservatives.