Place the roast in a deep ceramic or glass bowl, or large zip-lock. Add onions, peppercorns, cloves and bay leaf. Pour vinegar, water and cider vinegar over the meat and cover and chill for 3 days. turning each day. Remove the meat from the marinade, dry it well with paper towels and strain the marinade into a bowl. Reserve the marinade and onions.
In a Dutch oven, brown the meat on all sides in hot oil. Sprinkle meat with salt. Pour hot water. marinade, and onions around the meat and cook 3 1/2 hours, or until tender.
Remove the meat and keep warm. Add ginger snaps to cooking juices and boil 5 minutes. Add salt if desired.
Slice the meat across the grain and add to the hot gravy. Serve on heated platter. Serves 8.