Place the opened foie gras in a bowl set under a gentle stream of room-temperature water. Flush the foie gras about half an hour, or until the water runs clear and the foie gras warms enough to become pliable so you can manipulate it without breaking it.
Blot the foie gras dry and place it on a freshly sanitized work surface.
Slowly and gently pull the two lobes apart (A).
Use your fingers or a small, sharp knife to remove any visible membrane and surface blemishes from each lobe (B).
Lay each lobe on the worktable so the smooth side is down and the rough side is up. Starting at the narrow, top end of each lobe, slit open the lobe about halfway to the other end and about halfway into its depth (C).
Use your fingers and, if necessary, sanitized tweezers or needlenose pliers to remove the interior veins (D). Do so by grasping the thick top part of the vein network and pulling gently while holding back the meat of the liver with the other hand. Your goal is to extract the veins without breaking them and without disturbing the structure of the liver.
Sprinkle the interior and exterior of each lobe with the desired seasoning ingredients.
Wrap each lobe in plastic film, and then seal the wrapped lobes in a plastic bag.
Bury the bag of foie gras in ice and refrigerate 24 hours.