In a large Dutch oven or heavy-bottomed pot, heat the olive oil over medium-high heat. Add the ground beef and cook, breaking it up with a wooden spoon, for 5-7 minutes until it is fully browned and no longer pink.
Add the chopped onion and minced garlic to the pot with the beef. Cook, stirring frequently, for 3-4 minutes until the onion has softened and become translucent.
Sprinkle the taco seasoning over the meat mixture and stir for 1 minute until it is fragrant and the meat is evenly coated.
Pour in the beef broth and scrape the bottom of the pot with your spoon to lift any browned bits. Add the diced tomatoes, black beans, pinto beans, corn, and green chiles. Stir everything to combine.
Bring the soup to a boil, then immediately reduce the heat to low. Cover the pot with a lid and let the soup simmer gently for 15 minutes to allow the flavors to meld together.
Turn off the heat. Stir in the heavy cream and sour cream until they are fully incorporated and the soup appears creamy and smooth. Season with salt and pepper to taste before serving.