In a large cast-iron or other heavy skillet, cook sausage over medium heat just until no longer pink; drain. Add the onions, peppers and garlic. Cover and cook for until vegetables are tender, about 25 minutes, stirring occasionally. Add tomatoes and oregano. Cover and simmer until tomatoes are cooked, 5-6 minutes. Season with salt and pepper.
Meanwhile, hollow out bottom of each roll, leaving a 1/2-in. shell. (Discard removed bread or save for another use.) Toast rolls. Fill with sausage mixture. Freeze option: Freeze cooled meat mixture in freezer containers. To use, partially thaw in refrigerator overnight. Heat through in a saucepan, stirring occasionally; add water if necessary.