Scalloped Potatoes with meat

2 tablespoons cooking oil salt and pepper (optional) 3 tablespoons butter 3 tablespoons flour 1 1/2 teaspoons salt 1/2 teaspoon black pepper 2 teaspoons[...]

2 tablespoons olive oil 1 lb bulk Italian sausage 2 onions , thinly sliced 1 large red bell pepper , seeded and cut into 1/3 inch strips 1 large green bell[...]