Mix the dry rub: In a small bowl, mix together the chili powder, paprika, dried oregano, salt, and black pepper.
Pat the 3 lbs of chuck roast dry and rub it all over with the dry rub mixture, pressing it into every side.
Heat the oil in your crockpot or a large pan over medium-high heat. Sear the roast on all sides until you get a nice deep brown crust, about 4-5 minutes per side
Remove the meat.
(If using a pan for searing, complete steps 5, 6, and 7 in the same pan). Add the chopped onion into the pan with a little oil for about 5 minutes until soft.
Add the minced garlic and cook for about 30 seconds.
Pour in the beef broth to deglaze the pan (and transfer all of the contents back to the crockpot if needed)
Add the orange juice, juice from the 1 Lime, crushed tomatoes, and green chiles. Give everything a good mix.
Add the beef back in, cover, and reduce heat to low. Cook for around 8-10 hours or until the roast is fall-apart tender and shreds easily with a fork.
Shred the beef right in the remaining juices, and it should be ready to serve!
Crisp it up (optional but worth it): Spread the shredded beef on a sheet pan and broil for 4 minutes until the edges get crispy and charred—this is the move for tacos.
GLUTEN-FREE SUBSTITUTIONS: For those of you who need it, I always like to talk about substitutions to make this meal gluten-free. There are no concerns with these potatoes; you should be good for this one!