Crimson Coleslaw

4 tablespoons olive oil
3 tablespoons balsamic vinegar
2 tablespoons prepared white horseradish
1 cup (packed) coarsley grated, peeled, raw fresh beets (2 medium)
1 cup paper thin slices red onion
8 cups very thinly sliced red cabbage (about 1 1/4 pounds)

Whisk 4 tablespoons oil, vinegar and horseradish in large bowl to blend. Add beets, onion, and cabbage; toss to blend. Season to taste with salt and pepper. Let stand 10 minutes before serving, stirring occasionally.