For the chicken: Preheat broiler. Place chicken on a broiler pan. Sprinkle all over with salt, pepper, and cinnamon. Turn skin-side down, and transfer to broiler. Broil about 6 inches from the heat for 15 minutes. Turn the chicken, and broil until the skin is crisp and brown, about 15 minutes more.
For the raita: In a small bowl, stir together the cucumber, yogurt, sour cream, cilantro, and cumin. Season with salt and pepper. Serve chicken immediately with raita.