Using a mortar and pestle or spice grinder, grind the allspice, juniper, cloves, and peppercorns.
4 whole allspice berries, 6 whole juniper berries, 4 whole cloves, 8 whole black peppercorns
Rinse the beef and pat it dry with paper towels.
1 kilogram lean beef roast
In a gallon-size zip-top plastic bag, add the meat, ground spices, garlic, carrots, onion, celery, leek, bay leaves, thyme, wine, vinegar, and brown sugar; press out as much air as possible and seal the bag. Place the bag in a bowl just big enough to hold it (to prevent leaks and keep it upright). Marinate in the refrigerator for 3 to 5 days (longer marinating results in more tender, flavorful meat; if short on time, see the Notes).
2 cloves garlic, 2 medium carrots, 1 large onion, 2 celery stalks, 1 large leek, 2 bay leaves, 1 teaspoon dried thyme, 480 milliliters red wine, 480 milliliters red wine vinegar, 50 grams brown sugar
Preheat the oven to 320°F (160°C). Remove the meat from the bag and pat it dry with paper towels. Set a fine mesh sieve over a large bowl and strain the marinade. Reserve the liquid and the marinated veggies. In a large oven-safe pot with a lid, heat the butter and oil over medium-high heat until foamy, about 1 minute. Add the meat and sear on all sides, 1 to 2 minutes per side. Transfer to a large plate.
15 grams unsalted butter, 15 milliliters avocado oil
Add the strained vegetables and cook, stirring occasionally, until softened, about 5 minutes. Add the tomato paste and cook, stirring until fragrant, about 1 minute.
15 grams tomato paste
Return the meat to the pot. Add the bread, then pour in enough broth and reserved marinade (equal parts) to cover the roast two thirds of the way. Cover the pot and place in the oven; braise until the meat is tender but not falling apart, about 2 hours. (If the meat is extra lean, extend the cooking time by 30 to 60 minutes.) Rotate the meat halfway through cooking, adding more broth and marinade as needed.
1 heel of stale bread, 1 liter beef broth
Transfer the pot to the stove. Using tongs, transfer the meat to a carving board, cover it with foil, and let it rest for 15 minutes.
With a carving knife, slice the meat, against the grain, ½ inch (about 1 cm) thick.
Set a fine mesh sieve over a large bowl and strain the liquid. Return the liquid to the pot and add the raisins; simmer over low heat until the raisins have softened and added sweetness, about 15 minutes.
40 grams dark seedless raisins
In a small bowl, whisk the cornstarch and 1 tablespoon of water until no lumps remain. Stir into the sauce and cook, whisking occasionally, until thickened, 1 to 2 minutes. (For a thicker sauce, cook it slightly longer.) Season with salt, pepper, and brown sugar to taste. Return the sliced meat to the pot, or arrange it on a warmed platter and spoon the sauce over the top.
1 teaspoon cornstarch, salt and ground black pepper