1. Prepare the Brisket: Take your brisket out of the fridge about 30 minutes before cooking to bring it closer to room temperature. This helps it cook more evenly.
2. Make the Spice Rub: In a small bowl, mix together the salt, black pepper, dried thyme, dried rosemary, garlic powder, and onion powder.
3. Season the Brisket: Rub the olive oil all over the brisket, then sprinkle your spice mix generously, making sure it's fully coated. Let it sit for 30 minutes to absorb the delicious flavors.
4. Chop Aromatics: Dice half of your yellow onion and thinly slice the remaining half. Mince the garlic and dice the shallot.
5. Build the Sauce: In a saucepan, warm a little olive oil over medium heat. Sauté the diced onion, shallot, and minced garlic for about 5 minutes until they become fragrant and slightly softened. Stir in the cranberry sauce, Worcestershire sauce, and Guinness (or beef broth). Let this flavorful sauce simmer for 10 minutes to meld all the tastes together.
6. Preheat Oven: Preheat your oven to a low 250°F (120°C). This low and slow cooking ensures a super tender brisket.
7. Assemble the Roasting Pan: Pour half of your prepared sauce into a large roasting pan. Layer the thinly sliced onions over the sauce, then carefully place the brisket (fat side down) on top. Pour the rest of the sauce generously over the brisket.
8. Add Your Sides: Arrange the petite red potatoes, dried cranberries, and fresh rosemary and thyme sprigs around the brisket in the pan. These will soak up all the wonderful juices!
9. Slow Roast: Cover the entire roasting pan tightly with foil. Carefully place the covered pan in the center of your preheated oven and slow roast for 4 hours until the brisket is incredibly tender and fork-tender.
10. Rest and Serve: Once cooked, let the brisket rest, still covered, for 15-20 minutes before slicing. This is a crucial step that helps keep the meat juicy. Then, slice it against the grain for maximum tenderness and serve with the tender potatoes and rich pan sauce. Enjoy this easy and hearty holiday meal!