Cook the Ground Beef:
Heat a large pot over medium heat. Add the ground beef and cook until browned, breaking it into crumbles with a wooden spoon. Drain any excess fat.
Sauté the Aromatics:
Add the diced onion and garlic to the pot. Cook for 2–3 minutes until softened and fragrant.
Add Remaining Ingredients:
Stir in the black beans, kidney beans, diced tomatoes, tomatoes with green chilies, corn, broth, taco seasoning, and chili powder (if using). Mix well.
Simmer:
Bring the soup to a boil, then reduce the heat to low. Simmer uncovered for 20–25 minutes, stirring occasionally to allow the flavors to meld.
Adjust Seasoning:
Taste the soup and adjust with salt and pepper as needed.
Serve:
Ladle the soup into bowls and top with your favorite garnishes, such as shredded cheese, sour cream, or tortilla chips.