In a skillet over medium high heat, cook ground beef until browned. Add diced onion and cook for a minute or two more. Set aside.
In a large crockpot {covered with a liner} add the drained kidney beans, black beans, corn and crushed tomatoes. Add the jar of salsa, cooked ground beef and onion mixture, the taco seasoning packets and finally the beef broth. Stir everything together. Cover crockpot with a lid and cook on low for 6-8 hours or high for 4 hours.
When ready prepare your favorite toppings. Serve in a bowl and let everyone top with their favorites. Refrigerate leftovers for up to 4 days or freeze for up to 3 months.