Cut chicken into bite-sized pieces. Place in sauce pan and cook with 1/3 cup liquid from pineapple, or use water. Bring to boil then cook on medium heat for 15 minutes. Add vinegar, tomato sauce, sugar, salt, onion and green peppers to chicken. Simmer for 10 minutes and then add pineapple chunks. Mix corn starch with 1/4 cup cold water and add to pan, stirring constantly. Bring to boil cooking for 2 minutes to thicken. Let dish cool for 10 minutes before serving. Serve over rice.