In a very large skillet, cast iron if you have it, cook ground beef, gr pepper and onion until meat is browned, gr pepper and onion are tender, stirring to break up meat. Drain well. I then placed it in a slow cooker. If you want you can make the recipe in the large skillet, it cuts time down to about 25 minutes.
Add all other ingredients, except parsley. Cook until it starts to boil.
Add pasta and bring back to a simmer. Simmer, uncovered, stirring frequently. Sprinkle with fresh parsley and serve. Add cheese and sour cream, if desired.