How to Make It
Preheat the oven to 400°. Spread the walnuts in a pie pan and toast until fragrant, about 8 minutes. Place the carrots and beets in separate pie pans. Season the carrots with salt and pepper and drizzle with 1 teaspoon of the olive oil. Season the beets with salt and pepper, drizzle with 2 teaspoons of the olive oil and add the rosemary, thyme and garlic cloves. Cover both pans tightly with foil and roast the vegetables until tender, about 30 minutes for the carrots and 11/2 hours for the beets. Let cool. Discard the herbs and garlic.
Meanwhile, in a small bowl, whisk the lemon juice and balsamic vinegar with the remaining 1/3 cup of olive oil. Stir in the orange zest; season with salt and pepper.
Using a sharp knife, peel the oranges, making sure to remove all of the bitter white pith. Slice the oranges crosswise.
Peel the beets and thinly slice them crosswise. Arrange the beet slices around the edge of a large platter. Scatter the oranges and carrots over the beets. Drizzle 1/3 cup of the vinaigrette over the beets, carrots and oranges.
In a large bowl, toss the arugula with the remaining vinaigrette and season with salt and pepper. Mound the arugula in the center of the platter. Scatter the toasted walnuts, chives and lemon thyme around the platter and serve right away.