Pour 1/2 cup water in a 3 1/2- or 4-quart slow cooker. Combine the beets, carrots, and onion in a large bowl. Combine the orange marmalade, 2 tablespoons water and the ginger in a small bowl. Add to vegetables, toss to coat. Spoon vegetable mixture into cooker.
Cover and cook on low-heat setting for 6 to 8 hours or on high-heat setting for 3 1/2 to 4 1/2 hours.
To make sauce, combine in a small bowl sour cream, chives, and if desired, sherry. Serve sauce with vegetables.