Blend the dried chipotle peppers, minced garlic, cumin, vinegar, oregano, and salt with beef broth until smooth to create the marinade.
Place the beef chunks in a large bowl or zip-top bag and pour the marinade over, tossing to coat thoroughly. Let it sit for at least 15 minutes to absorb the flavors.
Heat a heavy-bottomed pot or Dutch oven over medium-high heat, then add a splash of oil. Once hot, add the beef chunks with marinade and sear until browned on all sides, about 5 minutes.
Add chopped onion to the pot and cook for another 3-4 minutes, until they become translucent and fragrant.
Pour in additional beef broth if needed, then reduce the heat to low. Cover the pot and let the beef simmer gently for about 40 minutes, until it is tender and easily pulls apart.
Uncover the pot and transfer the beef to a serving dish. Use two forks to shred the meat into tender, bite-sized pieces.
Taste the shredded beef and adjust seasoning if needed, adding more salt or vinegar for tang. Serve hot, garnished with fresh toppings or in tacos.