1. Preheat oven to 450°F.
2. Season chicken with salt and pepper. Arrange skin-side up, in nine x 13-inch baking pan. Bake, uncovered, for 20 to 30 minutes, until browned.
3. Combine vinegar, apple juice, tomato paste, and pineapple syrup with enough water to total two cups liquid. Pour into large bowl. Add soy sauce, ginger, onion, and pepper; stir well.
4. Lower oven to 350°F. Pour syrup mixture over chicken. Cover and bake for one hour.
5. Add pineapple to chicken. Cover and return to 325°F oven for 10 to 15 minutes or until chicken is tender and pineapple is heated through.
6. Remove chicken to platter; pour sauce into pot. Stir in dissolved cornstarch mixture and bring to a boil until thickened, stirring constantly. Pour sauce over chicken and serve.