Brisket is best when served the next day.
1 brisket flat (4-5 lbs.)
½ cup red wine
1 can (14 ounces) low-sodium beef broth
1 cup chili sauce or ketchup
¼ cup apple cider vinegar
¼ cup firmly packed light brown sugar
2 Tbs prepared horseradish
½ tsp dried thyme
1 bay leaf
Kosher salt and freshly ground pepper
2 Tbs vegetable oil
4 medium yellow onions, thinly sliced
Combine the wine, broth, chili sauce, horseradish, vinegar, brown sugar, thyme, and bay leaf in a medium bowl. Set aside.To prepare the brisket. Trim the fat on the brisket down to ¼ of an inch.
Season the brisket on both sides with kosher salt and pepper to taste. Heat 1 tablespoon of the oil in a 6-quart pot or Dutch oven over medium-high heat. When the oil is hot, add the brisket, fat-side down, and cook until golden brown, about 4 minutes. Turn the brisket over and cook until browned, 3 to 4 minutes more. Transfer to a plate. Add the remaining 1 tablespoon oil to the pot. Add the onions and cook, stirring occasionally, until they begin to caramelize, about 5 minutes. Place the brisket on top of the onions and cover with the sauce.
Cover the pot, place in the oven, and bake for 1-1/2 hours. Transfer the brisket to a cutting board, scrape off the excess fat, and cut across the grain of the meat into 1/8-1/4-inch-thick slices. Return the slices to the pot, overlapping them. Spoon the sauce back over the brisket, covering the meat well. Bake until the meat is fork tender, 1-1/2 to 2 hours more.
For the best flavor, let the brisket cool, then cover and refrigerate overnight. When ready to serve, preheat the oven to 350 degrees F. Cover and bake for 20 to 30 minutes.
Oven Temperature: 350 degrees F.