italian sausage recipe

- 1 lb (450g) Italian sausage (sweet or spicy, as you prefer) - 2 tbsp olive oil - 1 onion, finely chopped - 3 cloves garlic, minced - 1 bell pepper, diced (red or green) - 1 can (14.5 oz) diced tomatoes - 1 tsp dried basil - 1 tsp dried oregano - 1/2 tsp red pepper flakes (optional for extra heat) - Salt and black pepper to taste - Fresh parsley, chopped (for garnish) - Grated Parmesan cheese (optional) - Pasta or bread, for serving