Place ground beef and onion in a soup pot and cook until beef is reheated and onion is tender.
Add water, undrained tomatoes, kidney beans, tomato sauce, and taco seasoning mix. Simmer, covered, until hot.
Add cheese, sour cream, avocado, and tortilla chips to soup if desired. Add jalapenos or salsa for a spicier soup.
Notes
If you keep cooked ground beef and sautéed onions in your freezer, you can have this easy soup on the table in under 15 minutes.Toppings not included in nutrition calculation.