1. Heat the pine nuts in a dry skillet over medium heat until they begin to brown. Watch them carefully, as they will burn in a flash. Remove from the heat and transfer to a bowl. Set aside.
2. Peel the beets and slice them into bite-sized pieces. Remove the stems from the beet greens and slice the leaves into strips. Wash the greens thoroughly to remove any grit.
3. Heat the olive oil in a skillet over medium heat. Add the sliced red onion and garlic. Cook until the onions are tender and golden brown, about 10 minutes. Reduce the heat to medium low and add the beet greens. Cover and cook, tossing occasionally, until the greens are wilted, about 5 minutes.
4. Meanwhile, cook the beets in a pot of salted water until just tender, about 10-12 minutes. Remove the beets from the pot using a slotted spoon and set aside. Return the water to a boil and add the pasta. Cook according to the package instructions until al dente; drain.
5. Add the orzo to a bowl, along with the beets, pine nuts, beet greens and crumbled feta. Toss, season with salt and pepper to taste and serve.