Place the cut beets on a baking sheet and toss with the olive oil, thyme leaves, salt, and pepper. Roast for 35 to 40 minutes, turning once or twice with a spatula, until the beets are tender. Remove from the oven and immediately toss with the vinegar and orange juice. Sprinkle with salt and pepper and serve warm.lace the cut beets on a baking sheet and toss with the olive oil, thyme leaves, salt, and pepper. Roast for 35 to 40 minutes, turning once or twice with a spatula, until the beets are tender. Remove from the oven and immediately toss with the vinegar and orange juice. Sprinkle with salt and pepper and serve warm.