Take liver from milk and dry it. Sprinkle with salt.
Bring the goose fat to a high temperature in a small roasting pan. Put liver into pan and brown it quickly on all sides.
Add ¼cup water, the halved onion and a little more salt. Cover pan. Bake in a 400°F. oven till liquid is evaporated, which is generally at the time when liver is roasted rare.
Uncover the roasting pan. Increase oven temperature to 500°F., and let the liver brown for a few minutes.
Transfer liver to a serving platter. Mix paprika with the hot fat remaining in the pan; stir it fast, then strain over the liver.
Cool the liver, then put in refrigerator if you want to serve it as a cold appetizer. Or serve it immediately as a hot first course or a main course.
Soak liver in water instead of milk. Chop 1 garlic clove fine. Sprinkle it with salt and pepper and mash it with the flat side of a knife until it becomes a paste. Make 3 incisions in the liver and put some of the garlic paste in each incision. Roast as above.