On parchment-lined sheet pan, spread beets in single layer. Coat beets with cooking spray; sprinkle with salt and pepper. Roast until tender-crisp, 15-25 minutes. Cool.
In serving bowl, toss arugula, chopped roasted beets, oranges, parsley, sesame seeds (if using), and citrus vinaigrette dressing. Serve.
Citrus Vinaigrette
In a bowl, combine juice, zest, thyme, salt and pepper.
Whisk ingredients while drizzling olive oil into bowl to emulsify.