Saute onions, garlic and peppers in olive oil until lightly browned. Add in tomato paste and cook for 2-3 minutes. Deglaze pan with red wine and add in crushed tomatoes, fresh oregano, salt, sugar and fresh whole tomatoes. Cook sauce for approximately 20 minutes. Once sauce is at a slow simmer add in the clams & mussels until all are completely opened. While cooking bring salted water to a boil for the cavatelli. Cook and coo cavetelli, but do not rinse. When all the mussels and clams have opened serve the Fra Diavlo over a platter of warm cavatelli pasta and garnish with fresh chopped parsley. Offer grated Pecorino Romano cheese and additional crushed red pepper upon serving.