Toast the walnuts in a 375°F oven for 5 - 7 minutes, let cool, then coarsely chop.
Cut off the beet greens, discarding the stems. Wash the greens and cut into strips, about 1/2" wide.
Scrub the beets but don’t peel them. Steam or boil until tender, about 30 minutes. Let the beets cool slightly. You can leave the skins on or rub the skins off. (You might want to wear gloves.)
Slice them and toss with lemon juice, vinegar, one tablespoon of the olive oil, and salt to taste.
In a large skillet, heat the remaining oil over medium heat. Add onion and saute for 3 minutes. Add the greens and cook, stirring until wilted but still robust.
Blend the beets and greens and garnish with walnuts.
Optional: Sprinkle some crumbed sheep’s milk or goat feta on top before serving. (Recipe♦182)