Chop a small onion and garlic, then set them aside.
Heat your large pot over medium heat until it feels warm to the touch.
Add chopped onions and garlic to the pot, cooking until fragrant and translucent, about 5 minutes, stirring occasionally.
Stir in the ground beef, breaking it apart with your spoon, and cook until browned and no longer pink, about 8 minutes.
Drain excess fat if needed, then add diced tomatoes, corn, black beans, and taco seasoning to the pot.
Pour in the chicken broth, stirring everything together, then bring the mixture to a gentle simmer.
Let the soup simmer uncovered for about 20 minutes, stirring occasionally, until flavors meld and the soup thickens slightly.
Taste the soup and adjust seasoning with salt or more chili powder if desired.
Ladle the hot soup into bowls and top with shredded cheese, a dollop of sour cream, and chopped cilantro for added flavor and freshness.
Serve immediately and enjoy the comforting, flavorful bowl of taco soup.