Prep the brisket: Remove the corned beef from its package. Rinse briefly under cold water to remove excess salt on the surface, then pat dry very well with paper towels. This helps browning.

Trim if needed: Leave a thin layer of fat for moisture, but trim any thick, hard fat caps. A 1/4-inch layer is ideal.

Mix the rub: In a small bowl, combine Dijon, brown sugar, black pepper, garlic powder, and onion powder. Stir into a paste.

Season: Sprinkle the spice packet that came with the corned beef over the meat. Then spread the mustard mixture all over, coating the top and sides.

Wrap for stage one: Lay out a large piece of foil and lightly oil it. Place the brisket in the center, fat side up. Wrap tightly, crimping the edges to seal. This traps steam and keeps the meat tender early on.

Preheat: Heat the air fryer to 325°F (163°C) for 3–5 minutes. If your air fryer has a drawer, add 1/4 cup water to the bottom to catch drips and reduce smoking.

Cook low and slow: Place the foil-wrapped brisket in the basket. Cook at 325°F for 60–70 minutes for a 3-pound brisket, 75–85 minutes for a 4-pound brisket. The goal is to bring it close to tender without browning yet.

Unwrap and crisp: Carefully unwrap the foil. Drain any liquids from the foil and basket. Return the brisket to the basket, fat side up, uncovered.

Brown the top: Increase temperature to 370°F (188°C). Air fry 12–18 minutes, until the top is well browned and the internal temperature reaches about 190–200°F (88–93°C). This range gives a tender, sliceable texture.

Rest: Transfer to a cutting board and tent loosely with foil. Rest 15–20 minutes. This step is crucial for juiciness.

Slice: Slice against the grain into 1/8- to 1/4-inch slices for sandwiches, or thicker slices for dinner plates. For shredding, let it cool slightly more and pull with forks.