Preheat oven to 350F.
In a small mixing bowl, add the sausage, bread crumbs, parmesan, herbs, and egg. Stir together using a fork until evenly combined.
Sandwich your flank steak between two pieces of saran wrap. Pound out gently until it is mostly rectangular and approximately 1/4" thick- the longer your rectangle, the better.
Place the prosciutto slices evenly over the top of the steak. Add the sausage stuffing and spread it out evenly. Leave a 1/4" border around all sides.
Starting at the short side, roll up the steak and tie with cooking twine. Season with salt and pepper.
In a large dutch oven or other oven safe, lidded pot, heat the olive oil over medium heat. Add the onion, carrot, garlic and celery and saute for approximately 5 minutes.
Stir in the tomato paste, anchovy paste, then pour in the wine to deglaze the pan, using a wooden spoon to scrape up any browned bits on the bottom of the pan.
Add the tomatoes, tomato sauce and oregano.
Place the steak in the pot and pour sauce over. Cover and cook in preheated oven for 2 hours, or until the meat is tender.
Remove from pot and allow to rest for 15 minutes. Cut crosswise into slices and serve topped with additional sauce.