Place brisket leftovers in a baking dish. Pour over any juices or drippings that you saved to add moisture. You can also splash a little bit of apple juice or broth instead.
Cover the baking dish with aluminum foil and place the dish into the oven.
Heat brisket to an internal temperature of 160°F. This typically takes 20-25 minutes for sliced or chopped brisket.
Distribute heated brisket evenly across corn tortillas.
Top brisket with remaining toppings. Serve and enjoy!