Step 1: Prepare the Marinade

To start, you need to prepare the marinade that will infuse the roast with flavor. In a large resealable food storage bag, combine the balsamic vinegar, minced garlic, cranberry sauce, brown sugar, red pepper flakes, salt, and olive oil. The balsamic vinegar is key in giving the roast its signature tangy depth, while the cranberry sauce offers a sweet contrast. The brown sugar enhances the sweetness of the cranberries and balances the vinegar’s acidity, and the garlic adds a savory note.

Once all the ingredients are mixed together, you have your marinade ready. This mixture is the secret to making the roast beef tender and flavorful, so take your time to ensure it’s well-combined.

Step 2: Marinate the Beef

Now it’s time to marinate the beef. Use a sharp knife to pierce the roast all over, making small cuts that will allow the marinade to penetrate the meat. Once that’s done, place the roast in the resealable bag with the marinade and seal it tightly. Massage the marinade into the meat so it’s evenly coated, ensuring every inch of the roast is covered in the flavorful mixture.

Refrigerate the marinating roast overnight, or for at least 4 hours if you’re pressed for time. During this marination process, the flavors of the balsamic vinegar, garlic, and cranberry sauce will have a chance to soak into the beef, infusing it with their delicious profile. Don’t forget to turn the bag occasionally to ensure the marinade is evenly distributed.

Step 3: Preheat the Oven

Once the beef has marinated, preheat your oven to 350°F (175°C). This moderate temperature ensures the roast cooks evenly and remains juicy, while giving the balsamic and cranberry marinade enough time to work its magic on the beef.

Step 4: Sear the Roast

Next, you’ll want to sear the roast to develop a beautiful, golden-brown crust. In a large cast-iron pan, heat the vegetable oil over medium heat. Once the oil is hot, carefully place the marinated roast in the pan. Sear the roast for 2-3 minutes on each side until it develops a deep, golden-brown color.

Searing the roast is essential for two reasons. First, it locks in the juices, keeping the meat tender and moist. Second, it creates a flavorful crust that will enhance the overall texture of the roast. Be sure not to rush this step—allow the roast to develop a rich, deep color before moving on to the next step.

Step 5: Add the Marinade and Roast

Once the roast is seared, it’s time to deglaze the pan. Pour the remaining marinade into the pan, followed by the beef broth. Stir everything together to combine. Add the cranberries and thyme sprigs to the pan, and mix everything well.

Transfer the pan to the preheated oven and roast the beef for about 20 minutes per pound, or until the internal temperature reaches 140°F (60°C) for medium-rare. For medium doneness, aim for an internal temperature of 150°F (65°C). Use a meat thermometer to check the roast’s temperature, as it ensures your roast is cooked to perfection.

Step 6: Rest the Roast

Once the roast has reached your desired doneness, remove it from the oven and let it rest for at least 15 minutes. Resting is a crucial step because it allows the juices inside the roast to redistribute, ensuring every slice is juicy and tender. While the roast is resting, you can simmer the pan sauce on the stovetop to thicken it slightly.

Step 7: Serve

After the roast has rested, carve it against the grain into thin slices. Serve the slices of beef with the pan sauce, spooning the cranberries and juices over the meat. The cranberries will have softened during the roasting process, bursting with flavor and creating a glossy, flavorful sauce that complements the beef beautifully.