In a large bowl, combine the ground beef, tomato paste, onion, bell pepper, oats, egg, salt and pepper.
Shape the mixture into a loaf and place it in a 5x9 inch loaf pan.
In a small bowl, whisk together the ketchup, brown sugar and mustard. Slather the glaze on top of the meat loaf.
Bake for 1 hour or until the meat loaf is firm and cooked all the way through. Serve hot.