Sausage, Peppers, and Onions

Ok, another one of Matt's favorites. We usually eat it as a sandwich, but Matt has also ate it over rice. It's really good.

1/4 cup extra-virgin olive oil
1 pound sweet Italian turkey sausage
2 red bell peppers, sliced
2 yellow onions, sliced
1 teaspoon kosher salt
1 teaspoon freshly ground black pepper
1/2 teaspoon dried oregano
1/2 cup chopped fresh basil leaves
4 garlic cloves, chopped
2 tablespoons tomato paste
1 cup Marsala wine (ok, so I used a substitute)
1 (15-ounce) can diced tomatoes
1/4 teaspoon red pepper flakes, optional
4 to 6 fresh Italian sandwich rolls, optional