Season the chuck roast. Rub a thin even layer of Tajin hot sauce on all sides of the chuck roast to act as a binder. Sprinkle all sides of the chuck roast with the Texas rub. Then, mix chili powder, coriander, cumin, and paprika in a small bowl. Sprinkle the roast with the chili powder mixture.
Prepare the grill. While the chuck roast is resting, preheat a grill or smoker to about 250-275℉ with your choice of wood.
Smoke the chuck roast. Place the chuck roast on the indirect heat side of the grill. Smoke for about 3 hours, flipping the roast about halfway through the smoking time.
Braise the chuck roast. Preheat oven to 350℉. In a dutch oven, add the ingredients for the braising liquid - beef broth, juice from the can of pickled jalapeños, taco seasoning, garlic, and sliced onion. Stir to combine. Add the smoked chuck roast to the liquid, and spoon some of the liquid over the roast. Cover and bake at 350℉ for about 2-2.5 hours, or until the roast is tender and can be shredded easily.
Shred the beef roast. Remove the smoked chuck roast from the braising liquid and allow to cool slightly on a cutting board. Transfer the leftover braising liquid to a bowl (add a few tablespoons of water or beef stock to thin it out if needed - you should have about 1-1½ cups of liquid left). Pull and shred the beef. Then pour the reserved braising liquid over the shredded beef, and mix to combine.
Assemble the shredded beef tacos. Add a few tablespoons of high heat cooking oil to a griddle or skillet. Place a few corn tortillas in the oiled area, and let the tortillas heat up for a minute or two before adding shredded beef to one side of the tortilla. Fold tortilla over to create a taco and keep flipping and adding oil to the cooking surface as necessary until taco is browned and crispy.
Serve with your favorite toppings. When tortillas are golden brown, remove the tacos from the griddle. Add your favorite taco toppings and enjoy!