Preheat the oven to 400 degrees F.
In a large bowl, combine the onions, carrots and parsnips. Add the oil, herbes de Provence, salt and pepper; toss to coat evenly. Scatter the vegetables on a large nonstick rimmed baking sheet and roast for 20 minutes. Turn the vegetables over and roast until tender and beginning to brown, 15 to 20 minutes longer. Set the vegetables aside.
In a salad bowl, combine the arugula, pear slices and roasted vegetables. Add the Apple Cider Vinaigrette and toss until coated. Sprinkle with the chopped walnuts and serve.
In a medium bowl, whisk the vinegar, honey, salt and pepper until blended. Gradually whisk in the oil.