Heat oven to 425° F.
Trim the root and tip end of each beet, peel and cut into wedges.
On a piece of non-stick foil, drizzle 1 tablespoon of olive oil over the beets and onions.
Roast until tender, 20 to 25 minutes.
Meanwhile, heat the remaining tablespoon of oil in a skillet over medium-high heat.
Season the chicken with the pepper and cook until browned and cooked through, 5 to 6 minutes per side.
In a large bowl, toss the warm beet mixture with the kale, spinach and lime juice. Serve with the chicken.