Preparation - Saute the ground beef and onion in a skillet. Drain off the fat and place the beef mixture in a crockpot. Stir in the refried beans, chiles, chili sauce and shredded cheese. Cover and cook on low for 3 to 4 hours. Just before serving, stir in the sour cream and black olives (if using). Serve warm with tortilla chips or corn chips.