In a large skillet, cook and crumble the beef over medium-high heat. Add the onion and cook until the beef is no longer pink and the onion is translucent. Transfer to a 5 or 6 quart slow cooker.

Rinse and drain the beans and add to the slow cooker. Add all other ingredients except for the 2 cans of diced tomatoes and the can of green chilis.

In a blender or food processor, puree the diced tomatoes with the small can of chopped chilis until smooth; add to slow cooker.

Cover and cook on low for 6-8 hours.

Serve with toppings as desired.