Wash and trim the beets, removing both ends. Place them on a 12-inch square sheet of heavy-duty aluminum foil. Drizzle with the olive oil and season generously with salt and pepper. Seal up the foil packet and roast until the beets are fork-tender, about 1 hour.
In a large skillet over medium heat, cook the bacon until medium-crisp (or however you prefer your bacon). Transfer the bacon to a paper towel-lined plate. Increase the heat to high and add the kale, stirring to coat in the rendered bacon grease. Cover and cook for a few minutes, and then add the chicken stock and 2 tablespoons of the vinegar. Stir to combine, cover and allow to wilt for 6 to 8 minutes.
Peel and cut the beets into chunks and add them to the kale. Stir in the remaining 2 tablespoons vinegar. Add the bacon, stir to combine and season with salt and pepper. Serve immediately.