Remove the foie gras from refrigerator and let sit, covered, at room temperature for about half an hour. Remove from wrapping and with a small sharp knife, carefully remove and discard large veins or pieces of membrane. Season on all sides with salt and pepper, and lay foie gras smooth side up in a terrine or loaf pan of approximately the same size, preferably one with a lid. Tuck smaller or broken bits in with the larger pieces to form a solid loaf as far as possible, and press down gently. Pour the Sauternes over the foie gras, cover with lid or foil, and refrigerate overnight.

Remove the terrine from refrigerator and let sit at room temperature for 30 minutes. Preheat oven to 200 degrees F. Set the terrine in a slightly larger container such as a small roasting pan and surround with boiling water halfway up the sides of the terrine. Bake, covered, for 20-25 minutes and remove from oven. Let sit, still in water bath, for 20 minutes.

Uncover and remove any fat that has floated to surface and save (it may be used for flavoring other dishes). Gently weight the foie gras by laying the lid, if heavy, on top of it. Or cover with plastic wrap and foil and weight with one or two cans. Refrigerate, well covered, for three days. To serve, gently loosen edges with a knife, if necessary, and slice the terrine into 1/4 to 1/2 inch slices. Serve with toasted brioche, croutons or toast.