Heat the vegetable oil in a large pot over medium heat. Add chunks of beef and sear until browned on all sides.
Add the chopped onion and minced garlic, cooking until soft and fragrant.
Stir in the oregano, cumin, and beef broth. Bring to a simmer.
In a separate saucepan, soak the guajillo chiles in hot water for about 10 minutes until softened, then blend with a little soaking liquid to make a paste.
Add the paste to the pot and mix well. Cover and simmer for about 2 hours until the beef is tender.
Notes
Serve with warm tortillas and your favorite toppings.