1. Heat oil over medium to high heat and brown chorizo in a pot.
2. Add onions and sauté until tender.
3. Add mussels, carrots, celery, zucchini, green bell pepper, parsley beef broth, red wine, tomatoes, tomato sauce, tomato paste, Italian seasoning chili flakes , and garlic. Bring to a boil and simmer.
4. After 8 minutes (or when the shells have opened), remove from the soup the shells that have opened already. Place opened shells in a separate container and cover to keep warm.
5. Continue simmering the soup for around 25 minutes. Skim away the fat from the soup. Remove Season with salt and pepper.
6. When the soup is ready add the shells back to the soup. Sprinkle with cheese right before serving