3-pound rump or top round roast
1-1/2 cups apple cider vinegar
1-1/2 cups water
2 bay leaves
10 whole peppercorns
6 whole cloves
1 teaspoon salt
1 cup chopped onion
1/4 cup olive or Canola oil
1-1/2 cups warm water
1/2 cup cold water
1/3 cup all-purpose flour
Begin marinating the roast three days before serving. Combine the vinegar, water, bay leaves, peppercorns, cloves, salt and chopped onion in a deep non-metallic container (a one-gallon heavy-duty ziplock bag is even better). Set the roast into the marinade and refrigerate. Each morning and evening, turn the roast so that it is evenly marinated (if you're using a plastic bag, just turn the bag over).
To prepare the Sauerbraten, remove the roast from the marinade and dry it well. Discard all but 1/2 cup of the marinade.
In a Dutch oven, heat the oil over medium-high heat, add the roast and brown well on all sides. Position roast with fat side up. Lower heat, add the 1/2 cup of reserved marinade, cover, and simmer for 5 minutes. Add the warm water, cover, and simmer for 1-1/2 to 2 hours, or until roast is tender. Carve the roast and put on a heated platter.
For the gravy, combine the 1/2 cup of cold water with the 1/3 cup flour and mix until smooth. Add several tablespoons of the pan liquid to the flour mixture, a spoonful at a time, and mix well. Slowly pour the flour mixture into the pan juices while stirring. Continue stirring over medium heat until gravy thickens. (If you have a few flour lumps, don't despair; just strain the gravy into the container in which you will be serving it.) Pour some of the hot gravy over the sliced roast before bringing it to the table.
Note: You may wish, as some cooks do, to enliven your gravy by adding to it a tablespoon of butter, some cream or a little red wine. However, the gravy will be terrific without it.
The three days of marinating is essential, as far as I'm concerned. It deepens the flavor and contributes greatly to the tenderness of the roast.