Step 1 Wipe off any mold on the outside of the ham with a damp cloth dipped in a little vinegar. Soak the ham 24 hours in cold water, changing the water 3 or 4 times.
Step 2 After soaking, blanch the ham: Drain and put it in the stock pot with the calf's or pig's feet, veal bones and water to generously cover. Bring it slowly to a boil, skimming often and taking at least 20 minutes. Simmer 5 minutes, then remove the meats and rinse them with water. Taste a small piece of the ham, and if it is still very salty, blanch it again. Meanwhile, strip the parsley leaves from the stems and set aside the leaves. Tie the stems in cheesecloth with the bay leaves, thyme and peppercorns.
Step 3Put the ham, feet, bones, bag of aromatics, onions, leek, celery, carrots and wine in the pot. Add water to generously cover the ham, cover and bring the pot slowly to a boil. Remove the lid and simmer very gently, uncovered, until the ham is tender enough to be pulled apart with a fork, about 6 hours. Skim the pot often during cooking to remove fat and to keep the liquid clear; add water during cooking if necessary to keep the meats covered.
Step 4Let the pot cool for 15 minutes, then lift the ham out and set it aside. Let the ham cool to tepid, then pull it apart into large chunks with your fingers, cutting away any tendons and discarding bones and any skin. I find that the finished aspic is prettiest if I pull the ham from the bone and then pull it apart into 1-inch slivers with my fingers, rather than cutting cubes with a knife.
Step 5Strain the cooking liquid into a bowl, discarding veal bones, vegetables and spice bag. Skim the cooking liquid very thoroughly (if you have time to chill or freeze it so the surface fat solidifies, so much the better). Wipe out the stock pot, return the liquid to it and boil to reduce it until very well flavored, about 3 quarts. This may take half an hour or more. To give the parsley leaves bright color: Wash and dry them, chop and put them in a small bowl. Pour one-half cup boiling water over the parsley to set the color and leave to cool.
Step 6Test the cooking liquid after it is well reduced, to be sure it sets well: Freeze a saucer until very cold and add a tablespoonful of liquid. If it sets firmly and leaves a clear trail when you push it with a fingertip, it is ready to use. If it is soft, it will need 1 to 2 tablespoons gelatin; if very soft, play safe and use 3 to 5 tablespoons gelatin. To add the gelatin, put three-fourths cup water in a small saucepan. Sprinkle the gelatin and leave it until spongy, about 2 to 3 minutes. Stir the sponge into the hot cooking liquid until melted. Taste and adjust the seasoning -- it will probably need pepper, but possibly no salt. Strain it through cheesecloth into a metal bowl, stir in the parsley and water, shallots, and garlic. Taste, and adjust the seasoning again. If flavor needs brightening, stir in one-half cup more wine, or a squeeze (2 table