1Combine vinegar, water, onion, cloves, peppercorns and bay leaves. Place roast in a large bowl or crock. Pour vinegar mixture over the meat. Refrigerate for 3 days, turning the meat once or twice daily. After three days, remove meat and pat dry. Dredge in flour and brown on all sides, in a dutch oven or large pot, in oil and 1 tbsp. butter. Strain vinegar mixture; add 2 cups of mixture to meat. Cover and simmer for 3 hours. Melt remaining 2 tbsp. butter. Blend in 3 tbsp. flour and sugar. Heat until rich brown. Add this, along with remaining vinegar mixture to meat. Simmer 1 hour longer, until tender. Remove meat from pot. Stir in crushed gingersnaps into gravy and stir until thickened.