Preheat the oven to 350 degrees

In a small bowl stir together the chipotle powder, paprika, oregano, cumin, garlic powder & salt.

Place the chuck roast on a plate and sprinkle the spice mix all over the roast so that it is completely covered.

In a large pot or dutch oven arrange the sliced onions on the bottom, add in the orange juice, lime juice and beef stock. Place the chuck roast on top (if you have any leftover spice mix or any spice mix from the plate, add it into the pot over the onions). Cover with a lid and transfer to the oven. Cook for 3-3 1/2 hours until the beef is fall apart tender.

While the beef is cooking make the pickled onion. Cut a red onion in half and then very thinly slice the onion halves. In a small bowl whisk together the apple cider vinegar, honey and water and then add in the sliced red onion patting them down to ensure that they are all submerged in the liquid. Transfer to the fridge to marinate for 2-3 hours while the beef cooks.

In a small food processor or blender add the sauce ingredients (mayo, honey, lime juice and chipotle in adobo) and blend until smooth. Set aside

Once the beef is fall apart tender it, use two forks to shred it and return the beef to the pot. Stir it around so its coated in the sauce and onions. Turn the oven up to broil and return the pot to the oven for 2-3 minutes so the shredded beef becomes browned on top.

Warm the tortillas over the flame of the stove for 15-20 seconds per side until golden and browned in parts. Fill them with shredded lettuce, shredded beef, pickled onions, drizzle the sauce over and top with crumbled cotija cheese