Brown the ground beef in a large pot over high heat, breaking it up until browned, then drain the fat. Keep it moving so it browns evenly and doesn’t steam.

Add the black beans, pinto beans, corn, Rotel tomatoes, diced tomatoes, taco seasoning, ranch dressing mix, and beef or chicken broth to the same pot, then stir well. Make sure everything is evenly combined so the broth turns uniformly orange-red.

Bring the mixture to a boil over high heat, then reduce to medium and simmer for 15 minutes, stirring occasionally. Watch for a steady bubble and a thickened, lightly reduced texture.

Taste the soup and adjust seasoning as needed, then simmer 1 more minute if you want it to settle. Look for a balanced flavor across the broth and beans.

Serve the taco soup immediately with tortilla chips, cheddar, sour cream, jalapeños, and cilantro on top. The toppings should stay bright and fresh rather than fully softening.