Step 1: In a large pot or Dutch oven, brown the ground beef and chopped onion over medium-high heat. Break up the meat with a spoon as it cooks. Once the beef is fully browned and the onion is softened, drain any excess grease.
Step 2: Stir in the taco seasoning packet with the cooked beef and onion. Cook for 1-2 minutes, stirring constantly, to allow the flavors to bloom.
Step 3: Add the rinsed and drained black beans, kidney beans, drained corn, crushed tomatoes, undrained Rotel, ranch seasoning mix, and beef broth to the pot. Stir everything together until well combined.
Step 4: Bring the soup to a simmer over medium heat. Once simmering, reduce the heat to low, cover, and let it cook for at least 20-30 minutes, allowing the flavors to meld beautifully.
Step 5: Taste and adjust seasonings as needed. You might want to add a pinch of salt or a dash more chili powder depending on your preference.
Step 6: Ladle the hot taco soup into bowls. Serve with your favorite toppings such as shredded cheddar cheese, a dollop of sour cream or Greek yogurt, crushed tortilla chips, diced avocado, or fresh cilantro. A squeeze of fresh lime juice can brighten the whole bowl!