Generously season the brisket on all sides. Let it sit in the fridge for 30minutes.
At about 10:30am, put it in a crockpot with water.
Add taco sauce. Cover and set to low to cook for 6-7 hours.
An hour or so before serving, take the meat out and chop into small bites.
Place the chopped meat back into the pot, stir in the sauce, cover and leave it to "keep warm" setting.
Mix together chopped onion, cilantro, and season with salt & pepper. Set aside until ready to serve.
Lightly brush the corn tortillas with oil. Warm them in the oven a minute or 2.
Transfer the brisket into the bowl.
Assemble the condiments. Mexican cheese, salsa verde, onions & cilantro mixture, lime juice(use fresh if available), and taco sauce.