Saute onions in small amount of oil about 5 minutes. Add tomatoes and peppers and saute another 5 minutes. Add hot sauce and chicken broth and bring to a boil. Lower heat below boiling point and add cheese cubes, stirring constantly. After cheese has melted and blended, pour in water and cornstarch. Stir constantly untill thickened to desired consistency. Put in crock pot or fondue pot to keep warm.