makes 6-8 servings
1 (3 1/2-pound) beef brisket, flat cut, fat trimmed to 1/4 inch
1 tablespoon kosher salt
freshly ground black pepper
4 teaspoons vegetable oil, divided
2 large white onions, halved and sliced 1/2 inch thick
2 cups root beer
1 1/2 cups ketchup
4 teaspoons onion powder
2 teaspoons packed dark brown sugar
1 teaspoon garlic powder
1 teaspoon dried thyme leaves
1. If necessary, trim the fat from the brisket so that it is no more than 1/4-inch thick. (The brisket I used had already been trimmed to within an inch of its life, so I skipped this step.) Use a fork to poke holes all over the top and bottom of the brisket. Then rub both sides with salt -- use 1/2 tablespoon per side. Wrap the brisket tightly in plastic wrap, place on a platter and refrigerate for at least 6 hours.
2. Preheat the oven to 325 degrees.
3. Remove the brisket from the fridge, unwrap it, and use paper towels to gently wipe off any excess moisture. Generously pepper both sides of the brisket.
4. Add 2 teaspoons of vegetable oil to a large skillet and heat over medium heat. Place the brisket in the skillet, fat side down and brown for 4 minutes. To help it cook evenly, place a foil-wrapped heavy skillet (such as a Dutch oven or cast iron skillet) over top the brisket to flatten it out. After the bottom has browned, flip the brisket over and brown for 4 minutes on the opposite side.
5. Remove the brisket from the skillet and place on a platter.
6. Add another 2 teaspoons of vegetable oil to the skillet and add in the sliced onions. Saute until golden brown (about 12-15 minutes), stirring occasionally. Once cooked, spoon the onions into a 9x13 baking dish. Place the brisket over top the onions, fat-side up.
7. In a large bowl, stir together the root beer, ketchup, onion powder, brown sugar, garlic powder, and dried thyme. Pour this mixture over top the brisket.
8. Place a folded sheet of parchment paper over top the brisket. Then cover the entire baking dish with aluminum foil. Roast the brisket in the oven for 3 1/2 - 4 hours, or until the meat easily falls apart when a fork is inserted into it.
9. Remove the brisket from the oven, and let it rest, uncovered, for 30 minutes.
10. Remove the brisket from the baking dish and place it on a cutting board. Cut the brisket into slices against the grain. Use a spoon to remove any fat from the sauce, then place the sliced brisket back into the baking dish and coat each piece in the sauce before serving.