Preparation Preheat oven to 375°F. Wrap beets tightly in foil packages (3 beets in each). Place on baking sheet. Roast beets until tender, turning packages occasionally, about 1 hour 45 minutes. Unwrap beets; cool completely. Peel beets and cut into 1/4-inch-thick rounds. Place in large bowl. Combine vinegar and sugar in blender. Gradually blend in vegetable oil, then walnut oil. Season vinaigrette to taste with salt and pepper. (Beets and vinaigrette can be prepared 2 days ahead. Cover separately; refrigerate. Let beets stand 2 hours at room temperature before continuing. Rewhisk vinaigrette before using.) Toss beets with 1/4 cup vinaigrette. Toss plums and onion with § cup vinaigrette in another large bowl. Season with salt and pepper. Overlap beets around edge of platter. Mound spinach in center of platter; drizzle with some vinaigrette. Spoon plums and onion over salad. Sprinkle with goat cheese and serve.
Preparation Preheat oven to 375°F. Wrap beets tightly in foil packages (3 beets in each). Place on baking sheet. Roast beets until tender, turning packages occasionally, about 1 hour 45 minutes. Unwrap beets; cool completely. Peel beets and cut into 1/4-inch-thick rounds. Place in large bowl. Combine vinegar and sugar in blender. Gradually blend in vegetable oil, then walnut oil. Season vinaigrette to taste with salt and pepper. (Beets and vinaigrette can be prepared 2 days ahead. Cover separately; refrigerate. Let beets stand 2 hours at room temperature before continuing. Rewhisk vinaigrette before using.) Toss beets with 1/4 cup vinaigrette. Toss plums and onion with § cup vinaigrette in another large bowl. Season with salt and pepper. Overlap beets around edge of platter. Mound spinach in center of platter; drizzle with some vinaigrette. Spoon plums and onion over salad. Sprinkle with goat cheese and serve.