In a large skillet over medium-high heat, brown the ground beef with the diced onion until the meat is no longer pink.
Drain any excess fat from the skillet and add minced garlic, cooking for 1 minute until fragrant.
Stir in the chopped bell peppers, diced tomatoes, beef broth, uncooked rice, oregano, paprika, salt, and pepper.
Bring the mixture to a boil, then reduce heat to low and cover the skillet with a tight-fitting lid.
Simmer for 18 to 20 minutes until the rice is tender and most of the liquid is absorbed.
Remove the skillet from heat, sprinkle the shredded mozzarella over the top, and cover for 2 minutes until the cheese is fully melted.
Serve hot as a complete meal.