The gizzards are cooked for an hour in goose fat in order to exhale all their flavors and preserve their tenderness. Don't throw away the fat that comes with gizzards, you can reuse it in cooking, like butter or oil. Goose gizzards are more plentiful than duck gizzards and allow for more generous slices to put in salads. The ideal is to mince them and brown them in a pan for a few minutes before serving.