Slow-Cooked Brisket in Onion Gravy

Cut brisket into two or three pieces small enough to fit into a Dutch oven; pat dry. Heat 1 tablespoon oil in the Dutch oven over medium-high heat. Reduce the heat to medium and brown the brisket one piece at a time, about 2 minutes per side, adding an extra tablespoon of oil if necessary to prevent sticking. Transfer the brisket to a 5-quart (or larger) slow cooker.

Add the remaining 1 tablespoon oil to the pan. Add onions and cook, stirring occasionally, until softened, 3 to 6 minutes. Add garlic, thyme and pepper and cook, stirring, for 1 minute. Stir in tomato paste. Add beef broth and salt; bring to a boil.

Transfer the onion mixture to the slow cooker. Cover and cook until the brisket reaches desired tenderness (see Timing Tip), 4 to 5 hours on High or 8 to 10 hours on Low.

Transfer the brisket to a cutting board and slice or shred. Place in a serving dish; cover to keep warm. Transfer the gravy to a saucepan. Bring to a boil over medium-high heat and boil rapidly for 5 minutes to reduce slightly.

Meanwhile, mix butter and flour in a small bowl until smooth and creamy. Once the gravy has reduced, lower the heat to maintain a simmer. Stir in Worcestershire sauce. Whisk half the butter mixture into the gravy and return to a simmer. Cook, stirring, until it thickens slightly, 1 to 3 minutes. If the gravy does not thicken enough (it should have the consistency of a cream soup), add the rest of the butter mixture and repeat. Do not overcook. Serve the brisket with the gravy.