Place roast in 3 quart glass casserole. Combine vinegar, water, brown sugar, salt, pepper and cloves in another bowl; mix well. Pour mixture over beef. Turn beef to coat all sides. Add onions, carrots, celery, and bay leaf. Cover and marinate in refrigerator for 2 days, turning roast several times. Remove casserole from refrigerator and place in microwave oven. Microwave (Medium setting) 30 minutes. Turn roast over. Microwave 30-45 minutes until tender. Remove roast and keep warm. Skim fat from surface or broth. Strain broth and discard bay leaf. Place cooked vegetables and 1/2 cup broth in blender. Cover and blend until smooth. Combine vegetable mixture, remaining broth, gingersnap crumbs and browning gravy in same casserole. Microwave (High setting) 2 minutes or until gravy is slightly thickened. Stir some of the hot gravy mixture into sour cream. Then stir sour cream mixture back into casserole. Slice meat and serve with gravy. Makes 6 to 8 servings.