Prepare The Corned Beef

1. Rinse the corned beef & pat dry.
2. In a small bowl, mix together the mustard, vinegar, and the spice packet that comes with the corned beef.
3. Lay down a large piece of foil. Spread a thin layer of the mustard mixture on the foil. Place the corned beef on top of the mixture. Spread another layer of the mustard mixture on the top of the corned beef.
4. Wrap the corned beef in foil by bringing the shorter edges to the center, then fold them over each other to make a seam in the center. Fold in the edges to seal so that you create a foil packet around the corned beef.

Air Fryer

1. Preheat the air fryer to 350.
2. Add the prepared corned beef in the foil to the air fryer basket. Cook 60 minutes.
3. Unwrap the foil and spread another layer of the mustard mixture on top of the meat. Re-tent the foil around the meat and cook an additional 40 minutes. Optional: unwrap the foil and spread one last layer across the top. Cook uncovered for an additional 5 minutes to crisp the outside.
4.  Carefully remove the corned beef from the air fryer basket.
5. Let rest 10 minutes before slicing against the grain.