Preheat the oven to 375° F, and line a baking dish with aluminum foil.
Place beets and red onion on the aluminum foil. Coat well with 1 teaspoon olive oil and 1/2 tablespoon balsamic vinegar, and bake for 30 minutes.
While the beets are cooking, place the Brussels sprouts onto another parchment lined baking dish and sprinkle the remaining olive oil, balsamic vinegar, salt and pepper over them.
After the beets and onions have cooked for 30 minutes, add the Brussels sprouts to the oven. Let the Brussels sprouts cook together with the beets and onions for 10 minutes. After 10 minutes, add the thyme and turn over the Brussels sprouts. Roast for another 10-15 minutes until the Brussels sprouts are golden brown and soft. When done, remove from the oven and let cool.
Place the beets onto a cutting board, and peel and cut them into 1-inch pieces. Plate the Brussels sprouts with the beets and onions on a serving platter, and garnish with thyme sprigs.
Serving size: 1 cup, Calories: 100 grams, Fat: 3 grams, Saturated fat: 0.5 grams, Carbohydrates: 17 grams, Sugar: 7 grams, Sodium: 218 milligrams, Fiber: 6 grams, Protein: 5 grams, Cholesterol: 0 milligrams