In a large skillet over medium high heat brown grown beef, breaking apart. Add onions, and cook until soft. Stir in taco seasoning until the meat is evenly coated.
Add corn kernels, salsa, rice, tomatoes, and chicken stock. Stir until well mixed. Bring to a boil, then cover and reduce heat to a simmer. Cook for about 15 minutes, or until the rice is cooked through, and most of the liquid is absorbed.
Sprinkle cheese over the top of the dish. Cover and heat until cheese is melted.