Preheat oven to 425°F. Oil a large roasting pan and set aside. In a small bowl, combine paprika, cumin, salt, pepper, garlic, vinegar and oil to make a paste. Place onions in a large bowl and toss with 2 tablespoons of the paste. Rub chicken pieces with remaining paste and place in prepared pan, then cover with onions, peppers and lemon. Roast, basting occasionally with pan juices, until chicken is cooked through and vegetables are very tender, about 45 minutes. Remove from oven and let rest 5 minutes before serving.
* Note: If the chicken has been precut into eight pieces, simply cut each breast in half through the rib cage to ensure even cooking. Or, you can ask your butcher to cut a whole chicken into 10 pieces with breasts deboned.