Wrap beets tightly in foil and roast at 190°C / 375°F for 1½ hours, or until fork-tender. Let cool slightly, peel, and slice.
In a bowl, mix red onions, walnuts, garlic, fresh herbs, olive oil, lemon juice, salt, pepper, paprika, and optional spices.
Add beets to the salad and mix gently. Cover and refrigerate for at least 1 hour to let flavors develop.
