In a medium bowl, combine the marinade ingredients. Place the meat in a 2-gallon plastic bag and pour the marinade over the roas Tbsp Close the bag tightly and place in a flat glass dish. Refrigerate for 4 days, turning occasionally.
Preheat the oven to 300° F. Remove the meat from the bag, reserving the marinade. In a large roasting pan, heat the oil and 1 Tbsp of the butter or margarine over medium heat. Add the meat and brown on all sides, about 15 minutes. Pour the reserved marinade over the browned roast, cover, and bake for 4 hours.
Remove the meat to a heated platter. In a large saucepan, melt the remaining 5 Tbsp of butter or margarine. Add the flour and cook until the mixture bubbles, then pour in the pan juices and whisk until smooth.
Stir the sugar, gingersnaps, molasses, and raisins into the sauce; cook and stir until blended-the sauce will be fairly thick. Carve the meat into thick slices and serve with the sauce.
Servings: 4 to 6