Step 1

Heat 2 cups water and 2 cups vinegar in a large saucepan over medium heat. Add salt, cinnamon sticks, peppercorns, mustard seeds, ginger, allspice, and cloves. Bring to a simmer; immediately remove from heat. Stir in brown sugar until dissolved. Add Marsala wine. Let mixture steep until pan is cool enough to touch, at least 20 minutes.

Step 2

Place beef top round in a 1 1/2-quart resealable zip-top bag. Pour liquid around the beef. Pour in remaining water and vinegar and seal bag, removing as much air as possible. Place bag in a leak-proof container and refrigerate for 4 days, turning once a day.

Step 3

Preheat the oven to 350 degrees F (175 degrees C). Remove meat from bag and transfer into a roasting pan; reserve the marinade.

Step 4

Strain spices out of the marinade and discard. Pour 1/2 of the liquid into the pan with the meat and reserve the rest, about 4 cups, in a saucepan.

Step 5

Bake in the preheated oven until an instant-read thermometer inserted into the thickest part reads 165 degrees F (74 degrees C), about 1 1/2 hours. Transfer to a platter and let rest.

Step 6

Bring the 4 cups of remaining marinade to a simmer. Stir in sour cream and cook until thickened to your preference, 6 to 10 minutes. Slice beef against the grain and spoon the gravy on top.