Lay out chicken parts in baking dish and bake in 180ºC oven for 40 min. Cool them a bit and pour sauce (method below) over the chicken, cover and marinate in refrigerator for at least an hour, or overnight would be better. When ready to grill, drain excess sauce and reserve. Place chicken on prepared grill, skin side up, about 20 cm from heat. Grill, turning a few times, for about 20 minutes or until fork can be inserted with ease. Brush generously with reserved sauce during 20 minutes of grilling. When chicken is done, place on platter; top with remaining sauce and sprinkle with cheese, if you like. Sauce: In small saucepan, make sauce by mixing together onion, tomato sauce, taco sauce, molasses, vinegar, oil, salt, oregano, and pepper. Bring mixture to a boil. Remove from heat and cool 2 minutes.