Preheat oven to 350 degrees F (175 degrees C). Line a baking sheet with aluminum foil.
Rub the beets with 1 tablespoon of olive oil and place onto prepared baking sheet. Place in preheated oven, and bake until the beets can be easily pierced with a fork, 20 to 60 minutes depending on size. When done, allow to cool on the baking sheet until cool enough to handle, then remove and discard the skin, and cut the beets into wedges or slices.
Meanwhile, cut the beet greens in to 1/4 inch wide ribbons. Heat the remaining tablespoon of olive oil in a large skillet over medium heat. Add the onion; cook and stir until it begins to turn golden brown, about 10 minutes. Once the onions have begun to caramelize, stir in the beet greens and cook until they wilt. Add the beet slices and continue cooking until heated through. Season with sea salt and pepper before serving.
