Salt the brisket overnight. Pat the brisket dry with paper towels on all sides, then season generously with about 2 tsp kosher salt on all sides. Wrap tightly in a double layer of plastic wrap, then refrigerate overnight (or about 8 hours). Note: I’ve tested this without salting overnight and it still comes out delicious. I do it when I remember and have time. You do not rinse off the salt after brining.
Bring to room temperature. Allow the meat to sit out at room temperature for about 20-30 minutes before cooking. Meanwhile, season generously on all sides with 2 tsp more of kosher salt and 1 tsp freshly ground black pepper. Preheat an oven to 350°F (175°C).
Sear the brisket. In a large Dutch oven or pan, heat 3 Tbsp (45ml) neutral oil over medium-high heat. When the oil is hot and shimmering, add the brisket. Cook until browned, about 5-7 minutes per side. Use tongs to carefully transfer the brisket to a plate or cutting board. Reduce the heat to medium. Do not drain the drippings.
Sauté veggies. To the pot, add 2 Tbsp (30g) unsalted butter, halved onions, leeks, and shallots. Season with 1 tsp kosher salt, then cook, stirring occasionally, until softened, about 6-8 minutes. (This takes time, there’s a lot in there!) Add sliced garlic cloves, then cook about 1 minute more.
Deglaze. Add 2 Tbsp (30g) tomato paste, then use a spatula to help break it up as you stir. Increase the heat to medium-high, then pour in 1½ cups (360ml) red wine. Allow this to cook for several minutes until it’s reduced by about half. Next, add 2 cups (475ml) low-sodium beef broth (or chicken broth).
Return the meat to the pan, along with any juices that accumulated on the plate. Using kitchen twine, tie the fresh rosemary and thyme springs together, then add them to the pot along with 2 dried bay leaves.
Cook the brisket. Cover the pot with a tight fitting lid (or seal tightly with heavy duty aluminum foil), then transfer to the oven and cook for 3½ hours, or until the meat is tender. Carefully remove from the oven, then discard the herb bundle.
Cool slightly, then serve. The brisket will be easier to slice if you let it cool a bit. I’ll often make this the day before, cool completely, then slice and return the meat to the pan. It can be reheated directly in the pan the next day. However, if you’re serving it immediately, simply transfer it to a cutting board, lightly tent with foil, then cool for 20 minutes. Slice into ¼ to ½-inch thick slices across the grain (the muscle lines of the meat). Serve with creamy mashed potatoes or sides of your choosing, some of the braising liquid, and lots of onions and leeks spooned over the beef. Fresh thyme leaves on top is a nice finishing touch. Enjoy!