Fry the goose liver in hot oil until pink. Season with salt and ground pepper and keep warm. Pour off the drippings and deglaze with port wine. Reduce (boil down), add goose soup and bring to a boil. Cut the goose liver diagonally, swirl once in the sauce and arrange on the marinated lettuce. Sprinkle the lettuce lightly with the house marinade and balsamic sauce and arrange decoratively on the plates. Garnish with the cherry tomatoes.