Toast the dried guajillo and ancho chiles in a dry skillet over medium heat for 2-3 minutes until fragrant.

Combine the toasted chiles, quartered onion, garlic cloves, cumin seeds, dried oregano, and beef broth in a blender and blend until smooth.

Heat 1 tablespoon oil in a large pot or Dutch oven over medium-high heat and sear the beef chuck roast on all sides for about 5 minutes until browned.

Pour the blended sauce over the seared meat, season with salt, bring to a simmer, then reduce heat to low, cover and cook for 2 hours until the meat is tender.

Remove the meat from the broth and shred it using two forks.

Warm the corn tortillas in a skillet over medium heat for 20-30 seconds per side until soft and pliable.

Assemble the tacos by filling each tortilla with shredded beef, chopped onion, chopped cilantro, and crumbled queso fresco, then serve with lime wedges.

Serve the tacos with small bowls of the reserved cooking broth for dipping to enhance each bite.