Step 1

Heat oven to 400°F. Line 15x10x1-inch pan with foil. Spray second 15x10x1-inch pan with cooking spray.

Step 2

In large bowl, toss beets with 1 tablespoon of the oil. Arrange beets in single layer in foil-lined pan. Sprinkle with 1/2 teaspoon of the salt and 1/2 teaspoon of the pepper.

Step 3

In same bowl, toss sweet potatoes and parsnips with remaining 2 tablespoons oil. Arrange potatoes and parsnips in single layer in second pan. Sprinkle with remaining 1 1/4 teaspoons salt and 1/2 teaspoon pepper.

Step 4

Roast 40 to 45 minutes or just until vegetables are tender. Cool completely, about 20 minutes.

Step 5

In small bowl, mix dressing, parsley, horseradish and mustard with whisk. In large bowl, gently toss roasted vegetables with desired amount of dressing. Serve at room temperature or chilled over arugula with any remaining dressing.