Prepare Spice Rub: In a small bowl, stir together 2 Tablespoons Kosher salt, 2 Tablespoons brown sugar, 2 Tablespoons smoked paprika, 1 Tablespoon black pepper, 1 Tablespoon garlic powder, 1 Tablespoon onion powder, 1 ½ teaspoons cayenne pepper, and 1 teaspoon cumin.
Prepare Brisket: Trim fat cap of brisket to about ¼-inch if needed. Pat brisket dry with paper towels. Brush ¼ cup vegetable oil across the surface, then sprinkle seasoning all over, pressing it lightly into the meat so it sticks well. Optionally, wrap and refrigerate overnight for deeper flavor.
Prepare Roasting Setup: Preheat oven to 225 °F. Line a large roasting pan with aluminum foil and place a rack inside. Let seasoned brisket sit at room temperature for 30 minutes if you didn’t marinate it overnight.
Cook Low and Slow: Place brisket fat-side up on the rack. Cover the pan tightly with foil and bake for about 1 hour per pound (5-6 hours for a 5-pound brisket). (See the Notes section for guidance on using higher oven temperatures.)
Check for Doneness: Carefully remove foil. Check center with a meat thermometer. The brisket is ready when it reaches 195-205°F and feels tender when probed.
Add Crispy Exterior (Optional): Turn oven off. Return brisket, uncovered, for 15-20 minutes until the surface tightens and develops a light crust.
Rest Brisket: Tent with foil and rest for at least 1 hour so juices settle and slices stay moist.
Slice and Serve: Transfer brisket to cutting board and, using a sharp knife, slice against grain into ¼-inch slices. Adjust your angle if the grain shifts halfway through.