Place the 4-5 pound beef brisket flat cut on a large rimmed baking sheet. Pat the surface completely dry with paper towels to ensure proper seasoning adhesion. Measure 2 tablespoons of kosher salt and sprinkle it evenly over all sides of the brisket, including the edges. Transfer the baking sheet to your refrigerator and let the brisket rest uncovered for 12-24 hours.

After brining, remove the brisket from the refrigerator and let it sit at room temperature for one hour before cooking to ensure even heating.

Preheat your oven to 275°F. While the oven heats, combine 1 cup of beef broth, 2 tablespoons of apple cider vinegar, and 1 tablespoon of Worcestershire sauce in a measuring cup or small bowl. Stir these liquids together until fully incorporated. Pour the mixture into the bottom of your roasting pan.

Place a rack in your roasting pan and position the seasoned brisket on the rack with the fat side facing up. Insert an instant-read thermometer into the thickest part of the brisket. Place the roasting pan in the preheated 275°F oven on the middle rack. Cook undisturbed for 4-5 hours, or until the internal temperature reaches 195-203°F.

When the instant-read thermometer shows 195-203°F, carefully remove the roasting pan from the oven. Transfer the brisket to a clean cutting board, tent it loosely with heavy-duty aluminum foil, and let it rest for exactly 60 minutes.

After resting, use a sharp chef’s knife to slice the brisket against the grain into ¼-inch thick slices.