To make the filling, heat 1 tablespoon of the oil in a sauté pan over a medium flame and cook the sausage until it begins to sizzle. Lower the heat and continue cooking, turning the sausage occasionally, until it has cooked through, about 15 minutes. Remove to a plate to cool. Drain all but 1 tablespoon of the accumulated fat from the pan and add the peppers, onion, and