Heat a large, heavy-bottomed skillet over medium-high heat. Add ground beef and cook, breaking it apart with a wooden spoon, until no longer pink and internal temperature reaches 160°F (71°C), about 5-6 minutes. Drain any excess fat.
Add diced onion and bell pepper to the skillet with the beef. Sauté for 3-4 minutes, stirring occasionally, until softened.
Stir in the taco seasoning and cook for 1 minute until fragrant. Add the uncooked rice and stir to coat in the spices, toasting it slightly for 30 seconds.
Pour in the beef broth, diced tomatoes with their juices, black beans, and corn. Stir well to combine everything. Bring the mixture to a boil over high heat.
Reduce heat to low, cover tightly with a lid, and simmer for 20-25 minutes. Avoid lifting the lid to keep steam in; check at 20 minutes. Rice should be tender and liquid absorbed.
Remove the skillet from heat. Sprinkle shredded cheese evenly over the top, cover again, and let it sit for 3-5 minutes until cheese is fully melted. Fluff the rice gently with a fork. Serve hot, garnished with fresh cilantro and a dollop of sour cream.