Cut the onions and carrots into half, fry them slightly in a dry frying pan until brown burns. Put pieces of shank in a deep wide saucepan and cover with 6 liters of cold water. Bring water to the boil under medium heat, add salt and skim off the foam. Add onion, carrot, parsley, peppercorn and bay leaf. Cook on the lowest heat for 8 hours. The broth should not boil: boiling should be scarcely noticeable. Take the shank out of the broth, remove the meat from the bones and take to the fibers. Put the garlic through a wringer. Place the meat in rectangular pans, top with garlic. Cover with the broth and refrigerate for 4 hours. Remove fat from the top. Serve cold, with creamy horseradish.