Set your Dutch oven over medium-high heat. Add the ground beef and cook, breaking it up with a wooden spoon, until no pink remains, about 6-8 minutes. Drain excess fat if needed, leaving about 1 tablespoon in the pot. Add the diced onion and cook until softened and just starting to brown at the edges, about 4 minutes. Stir in the garlic and cook until fragrant, 30 seconds.

Sprinkle the taco seasoning over the beef and stir to coat everything evenly. Pour in the enchilada sauce, diced tomatoes with their juices, drained black beans, and chicken broth. Stir well, scraping up any browned bits from the bottom of the pot. Bring to a boil, then reduce heat to maintain a gentle simmer. Cook uncovered for 15 minutes to let the flavors meld.

Reduce heat to low. Add the cubed cream cheese and stir constantly until completely melted and smooth, about 3-4 minutes. Gradually add 1.5 cups of the shredded cheddar, stirring between each handful until fully melted. Do not let the soup boil at this stage or the cheese may separate. The soup should be thick and creamy.

Taste and adjust seasoning with salt if needed. Ladle into bowls and top with the remaining 0.5 cup cheddar, tortilla strips, a dollop of sour cream, and fresh cilantro. Serve immediately while hot and melty.