Carefully wash and clean the livers, removing the fat and connective tissue. Cover with the white wine with a few peppercorns and a bay leaf and set aside to soak for 6 to 7 hours in the refrigerator.
Before cooking the livers, prepare the onion sauce. Place the onions and salt in a medium-size pot and cover with water. Cover the pot and boil over low heat until the onions fall apart. D