Wash heart thoroughly. Remove veins and arteries. Rub inside and outside with salt and pepper. Fill with highly seasoned poultry stuffing. Sew or skewer. Brown in hot fat. Add 1 cup water and 1 cup canned tomatoes. Cover. Bake in slow oven (300 F) until tender, about 4 hours. Place whole onions around heart the last 30 minutes of cooking. 6 servings.