01 -
Remove brisket from refrigeration 30 minutes prior to cooking to reach room temperature. Combine salt, black pepper, dried thyme, dried rosemary, garlic powder, and onion powder in a small bowl. Rub olive oil over brisket, then season generously with the spice mixture. Let rest for 30 minutes.
02 -
Dice half the yellow onion and thinly slice the remaining half, setting aside separately.
03 -
Heat a saucepan over medium heat and add olive oil, swirling to coat. Add diced onion, shallot, and minced garlic; sauté for 5 minutes. Stir in cranberry jelly, Worcestershire sauce, and Guinness beer. Simmer for 10 minutes until sauce thickens slightly.
04 -
Set the oven temperature to 121°C.
05 -
Pour half of the sauce into a roasting pan. Arrange sliced onions in the pan and place the brisket fat side down atop them. Spoon remaining sauce evenly over the brisket.
06 -
Surround brisket with red potatoes, dried cranberries, and fresh rosemary and thyme sprigs. Cover the roasting pan tightly with aluminum foil.
07 -
Place the roasting pan on the center rack of the oven and cook for 4 hours.
08 -
Slice the brisket against the grain and serve alongside the roasted potatoes and sauce.