Preparation Whisk orange juice, vinegar, and mustard in small bowl to blend. Gradually whisk in oil. Season vinaigrette to taste with salt and pepper. (Can be made 1 day ahead. Cover and refrigerate.) Combine Jerusalem artichokes, arugula, and Parmesan in large bowl. Drizzle with vinaigrette and toss to coat. Divide among 6 plates and serve. Test-kitchen tip:Because Jerusalem artichokes discolor quickly, peel and slice them just before serving.
Preparation Whisk orange juice, vinegar, and mustard in small bowl to blend. Gradually whisk in oil. Season vinaigrette to taste with salt and pepper. (Can be made 1 day ahead. Cover and refrigerate.) Combine Jerusalem artichokes, arugula, and Parmesan in large bowl. Drizzle with vinaigrette and toss to coat. Divide among 6 plates and serve. Test-kitchen tip:Because Jerusalem artichokes discolor quickly, peel and slice them just before serving.