This is wonderful served with potato pancakes or potato dumplings and red cabbage.
1 boneless rump roast (about 4 pounds)
4 cups water
2 cups red wine vinegar
2 tablespoons granulated sugar
1 medium-size onion, finely chopped
3/4 cup celery, finely chopped
1/4 teaspoon salt
Pinch of pepper
1 teaspoon mixed pickling spices
24 crushed gingersnaps (1 1/2 cups crumbs)
Trim meat of all but a thin layer of fat. Place in a large glass bowl. Add water, vinegar, sugar, onion, celery, salt, pepper and pickling spices to bowl, stirring to mix. Cover with plastic wrap; refrigerate 4 or 5 days, turning meat each day.
Remove meat from marinade; reserve marinade; pat meat dry with paper toweling. Heat shortening in Dutch oven. Brown meat on all sides (about 15 minutes).
Remove fat from pan. Pour marinade over meat. Roast uncovered at 350 degrees F for 30 minutes.
Cover; continue roasting for 2 1/2 to 3 hours longer, or until meat is tender.
Remove meat to platter. Strain marinade; remove fat and return marinade to pan. Stir in gingersnap crumbs. Heat until thickened; strain again.
Slice meat and serve with gravy.