01 - Heat a large, deep skillet or Dutch oven over medium-high heat. Add ground beef and cook, breaking it apart, until browned. Drain excess fat.
02 - Add diced yellow onion, red bell pepper, and minced garlic to the skillet. Sauté for 3-4 minutes until softened.
03 - Stir in taco seasoning, salt, black pepper, and crushed red pepper flakes. Cook for 1 minute until fragrant.
04 - Add drained black beans, drained corn, dry elbow macaroni, beef broth, and diced tomatoes with their juices. Stir to combine thoroughly.
05 - Bring the mixture to a boil, then reduce heat to medium-low. Cover and simmer for 12-15 minutes, stirring occasionally, until the pasta is tender and most of the liquid has been absorbed.
06 - Remove the skillet from heat. Sprinkle shredded cheddar cheese evenly over the top. Cover and let stand for 2-3 minutes to allow the cheese to melt.
07 - Serve hot, garnished with chopped cilantro, sliced green onions, and sour cream if desired.