In a large pot add ground beef and cook on medium heat until browned and all juices came out, about 10 minutes. Drain grease, if necessary. Season with salt and pepper to taste.
Add onions, peppers, and garlic, cook for about 3 minutes.
Stir in canned beans, tomatoes (with juices) and chili powder. Mix well. Bring mixture to boil. Cover the pot and cook over low heat for 20-25 minutes; stirring occasionally.
Serve topped with cheese and sour cream, if desired.