Marinating the meat. Crush the peppercorns, juniper, and allspice in a mortar or in a small plastic bag using a rolling pin. Transfer them to a small saucepan and add the bay leaves, cloves, salt, red wine vinegar, red wine, and onion and bring to a boil. Turn off the heat and let cool. You can transfer the marinade to a large bowl to quicken the process.
Add the beef to the bowl and coat all sides with the marinade. Cover and let sit in a fridge for 48-72 hours, turning the meat a few times a day.
Preheat the oven to 300°F (150°C).
Browning the meat. Transfer the beef to a plate, scraping any solids that stick to it back into the marinade.We will need it later. Pat the meat dry with paper towels.
Heat the butter and oil in a large Dutch oven (6-7 quart / liters), add the meat, and brown it well on all sides. About 25 minutes total. Transfer the beef back to the plate. Pour off the fat from the pot and deglaze it adding the reserved marinade and scraping browned bits. Bring to a boil and add the beef. Cover with parchment paper, pressing it down so it almost touches the beef and cover with a lid.The parchment paper has to hang over the sides of the pot. Transfer to the oven.
Cook the meat for 1 1/2 hours, then turn it over and continue braising for another 1 1/2 hours or until fork-tender.
When done, transfer the meat to a plate and cover to keep warm.
The gravy. Strain the cooking liquid into a saucepan. Let sit for a few minutes and skim off the fat. Add the gingersnap, raisins, and sugar, and bring to a boil. Boil for about 5 minutes, whisking, to thicken the sauce a little bit. Turn off the heat and whisk in the sour cream. Taste the sauce and add seasonings if needed.
Cut the meat into thick slices, pour some gravy over it, and serve. Enjoy!