In a large pot, add lean ground beef and onions over medium high heat. Cook until beef is cooked and onions are softened.
Stir in black beans, corn, diced tomatoes, taco seasoning, green chilies, taco sauce and chili powder. Bring to a boil. Reduce to heat medium low and simmer, uncovered, for 30 minutes.
Ladle into bowls and top with garnishes, if desired.