Preparation Preheat oven to 375°F. Wrap beets in double thickness of aluminum foil. Cut onions through root end into 3/4-inch-thick wedges. Place onion wedges in medium bowl; toss with oil. Arrange onion wedges, cut side down, on baking sheet. Place beets directly on oven rack. Roast beets until tender, about 1 hour 45 minutes and onions until brown and tender, turning once, about 1 hour. Peel beets; cut into 1/2-inch pieces. Chop onions coarsely. Using on/off turns, coarsely chop cranberries in processor. Add beets and onions; blend briefly to chunky consistency. Transfer to bowl; mix in honey, horseradish, vinegar, salt and pepper. Cover and refrigerate at least 1 day. (Can be made 4 days ahead. Keep refrigerated.)
Preparation Preheat oven to 375°F. Wrap beets in double thickness of aluminum foil. Cut onions through root end into 3/4-inch-thick wedges. Place onion wedges in medium bowl; toss with oil. Arrange onion wedges, cut side down, on baking sheet. Place beets directly on oven rack. Roast beets until tender, about 1 hour 45 minutes and onions until brown and tender, turning once, about 1 hour. Peel beets; cut into 1/2-inch pieces. Chop onions coarsely. Using on/off turns, coarsely chop cranberries in processor. Add beets and onions; blend briefly to chunky consistency. Transfer to bowl; mix in honey, horseradish, vinegar, salt and pepper. Cover and refrigerate at least 1 day. (Can be made 4 days ahead. Keep refrigerated.)