01 - 
                Combine the onion, carrots, leek, red wine vinegar, dry red wine, beef stock, granulated sugar, golden raisins, bay leaves, juniper berries, cloves, kosher salt, and black pepper in a pot. Bring to a boil over medium-high heat, then reduce to a simmer for 10 minutes. Remove from heat and allow to cool completely.
              
              
              
                02 - 
                Place the rump roast in the cooled marinade, ensuring it is fully submerged. Cover and refrigerate for at least 4 days, turning the meat every 12 hours for even marination.
              
              
              
                03 - 
                Preheat the oven to 150°C. Remove the beef from the marinade, pat dry with paper towels, and reserve the marinade. Season the beef on all sides with salt and pepper, then dredge in flour and shake off the excess.
              
              
              
                04 - 
                Heat 3 tablespoons of lard or vegetable oil in a Dutch oven over medium heat. Brown the beef on all sides for about 10–15 minutes. Remove excess fat if needed.
              
              
              
                05 - 
                Return the reserved marinade to the pot with the beef and bring to a gentle simmer. Cover with a tight-fitting lid and transfer to the preheated oven. Braise for 3 hours, checking for tenderness with a knife. If not tender, cover and cook for an additional 45 minutes before checking again.
              
              
              
                06 - 
                When the beef is tender, transfer it to a platter and tent with foil. Strain the solids from the cooking liquid. Return the liquid to the pot, set over medium heat, and whisk in the crushed gingersnap cookies. Add optional raisins and simmer for 10 minutes, stirring occasionally. Adjust seasoning with salt and pepper if necessary. If a thicker consistency is desired, whisk in a cornstarch slurry.
              
              
              
                07 - 
                Slice the meat against the grain using a sharp knife, arrange on a serving platter, and pour the sauce over the slices. Serve remaining sauce on the side.