In the bottom of a large pot over medium-high heat, brown the ground beef for about 7-10 minutes, until no longer pink. Drain if desired.
Add 2 tablespoons (28 g) taco seasoning (⅔ of the total amount) and ¾ cup (177 mL) of broth. Simmer for a couple of minutes, until the liquid is mostly gone.
Add the remaining broth, diced tomatoes (with liquid), and remaining tablespoon of taco seasoning. Stir together. Bring to a gentle boil and simmer for about 8-10 minutes.
Remove from heat. Wait 2 minutes, then stir in the ranch dressing. If desired, garnish with shredded cheddar cheese and cilantro.