In a large pot or Dutch oven, brown the ground beef over medium-high heat. Drain off any excess grease.
Add the chopped onion to the pot and cook until softened, about 5 minutes.
Stir in the minced garlic and cook for 1 minute more until fragrant.
Add the rinsed and drained kidney beans and black beans, drained corn, diced tomatoes with green chilies, tomato sauce, and beef broth to the pot.
Stir in the taco seasoning and chili powder.
Bring the soup to a boil, then reduce heat to low, cover, and simmer for at least 20 minutes, or until flavors have melded.
Season with salt and pepper to taste.
Serve hot, garnished with your favorite taco toppings.
Notes
For a slow cooker version, brown the beef and onion on the stovetop, then transfer everything to a slow cooker and cook on low for 6-8 hours or high for 3-4 hours.
This soup freezes well. Let it cool completely before transferring to freezer-safe containers.
Adjust the amount of taco seasoning and chili powder to your spice preference.