This is the recipe my German-heritage mother always worked from.
Saurbraten Recipe
1 beef round roast
2 teaspoons salt
1 teaspoon black pepper
4 onions, sliced
2 carrots, sliced
2 ribs of celery, sliced
4 whole cloves
4 black peppercorns
2 bay leaves
4 cups red wine vinegar
6 tablespoons butter
1/2 cup flour
2 tablespoons sugar
8 gingersnaps, crushed
Wipe roast with a damp cloth, season with salt and pepper, and then place in very large pot.
In a medium bowl, combine the onions, carrot, celery, cloves, peppercorns, bay leaves, vinegar, and 5 cups water and sugar. Pour mixture over meat – add water if mixture doesn’t cover meat completely. Cover and refrigerate for 4 days, turning daily. On the 5th day, remove meat with slotted spoons and reserve the marinade.
Brown meat in convection oven (fi you have one – if not, your regular oven will do). (I think this is where the butter comes in, but the recipe never said. Rub it on the meat to encourage browning.) Then place in deep roasting pan with marinade and cook, covered, until done, about 3 hours.
Remove the meat from the oven and crush ginger snaps into marinade, thicken with flour. Pour gravy over saurbraten. (Or, slice saurbraten and then serve in gravy.)
Excellent served over fried egg noodles or mashed potatoes.