Mix all the seasonings together. Pat the roast dry with some paper towel. Rub the roast all over with the seasoning mix.
For the Oven: Preheat the oven to 300º. In a large 4-5 qt heat olive oil. Add the chopped onion and sauté . Once the onion is translucent, add the garlic and sauté. Next add the roast and sear it on each side for about 2 minutes on medium/high heat.
Add the broth, squeeze orange juice, chipotle peppers and adobo sauce, green chilies. Bake in the oven, uncovered for 3-4 hours. Be sure to check on it after 3 hours. Once the beef easily shreds with a fork and its super tender, it's ready!
For the crockpot: Set the crockpot to high. Add the oil to the bottom, add the roast and then pour the broth, chipotle peppers, chiles, orange juice, raw onions and garlic to the crockpot. Cover, cook on high for 4-5 hours. On low, 6-7 hours. Please note, if the roast isn't easy to shred, it needs more time to cook!
Once the roast is tender, shred it with two forks on a cutting board or in the dish it cooked in, just be sure the dish is cool enough to handle. Heat the tortillas however you prefer. Add the shredded beef, cheese and toppings of choice (pico de gallo, avocado, sour cream, pickled onions whatever you want!). Garnish with fresh cilantro and a drizzle of the beef juice. Enjoy!
Note: Enjoy the tacos as is, or pop them into the oven on broil low for 1-2 minutes to melt the cheese and crisp the beef. Both are wonderful and delicious.