Brisket is a tough cut, but with careful cooking, it becomes one of the flavorful and desirable cuts of beef and is taken from the bottom front of the cow, just below the neck. Traditionally, brisket is braised for several hours on low heat or barbecued on a grill over low heat until the outside develops a strong char and the inside stays juicy. You don’t have a good reason to mess with these cooking methods, which are as close to perfection as it gets – so, if you want to cook sliced brisket for a sandwich, all you do is to cut and heat up slices of leftover brisket after letting it stew in its juices overnight.
Cut the brisket into several slices of uniform thickness -- about 1/2 inch or to your preference. Cut cross-wise.
Heat a small amount of oil in a skillet until just before smoking.
Place the brisket slices in a single layer in the skillet and season the side that faces up, as desired. Add some of the juices from the refrigerated brisket pan, if you wish, to add more flavor to the brisket slices. Cook for about 1 to 2 minutes on the first side, until heated and a brown color develops.
Flip the slices over and season the other side. Cook for about 2 to 3 minutes or until the brisket is hot.
Remove the brisket slices from the pan and use immediately to build your sandwich. Cook any remaining brisket slices that wouldn't fit in a single layer.