In a large skillet, heat a little oil over medium heat. Add the diced onion and bell pepper, sautéing until the onion is translucent, about 5 minutes.
Add the minced garlic to the skillet and cook for an additional minute until fragrant.
Add the ground beef to the skillet, breaking it up with a wooden spoon. Cook until browned and no longer pink, about 5-7 minutes. Drain excess fat if necessary.
Stir in the chili powder, cumin, salt, and pepper. Mix well to combine and let it cook for an additional 2 minutes.
Meanwhile, prepare the rice according to package instructions using water or broth. Once cooked, set it aside.
To the skillet with the beef, add the corn and black beans, stirring until everything is heated through for about 3 minutes.
To serve, place a portion of rice in each bowl, top with the beef mixture, and add any desired toppings like diced tomatoes, avocado, shredded cheese, sour cream, or chopped cilantro.