Heat the oil in a large pan, over medium heat. Add the sausages and cook, turning frequently. You want them browned all over and this takes about 10 minutes. Add the onions and stir up the browned bits on the bottom of the pan.
Then after another 2 minutes, add the peppers, garlic, salt, pepper and dried oregano. After lowering the heat, cook for another 5-10 minutes, until the vegetables are tender and the sausages are cooked through. Spoon into the rolls and serve immediately.