In a large pot, heat oil over medium-high heat and sear the seasoned beef shoulder roast until browned, about 5-7 minutes. Pour in the beef broth, then add chopped garlic, onion, and a bay leaf. Bring to a simmer, cover, and cook for about 2 hours until the beef is fork-tender. Remove the beef and allow it to rest; reserve the broth for later.

While the beef cools, prepare the sauce by soaking guajillo chiles in hot water for 15 minutes. Once softened, blend the chiles with reserved broth, garlic, cumin, salt, and pepper until smooth. Pour the sauce into a pot and heat it on medium until bubbling, then stir in the shredded beef and cook for another 5-10 minutes until heated through.

While the sauce is heating, soak the corn husks in a large bowl of hot water for about 30 minutes. This process makes the husks pliable, ideal for wrapping your beef tamales. Keep an eye on them; they should feel soft and easy to bend when ready.

Once your husks are ready, take one husk and spread about 2-3 tablespoons of prepared masa across the center, leaving space at the edges. Add a generous spoonful of the beef filling and fold the sides over the masa. Then, fold the bottom of the husk up and secure it tightly. Repeat this process until all tamales are assembled.

In a large steamer pot, arrange the tamales upright, standing them on their folded ends. Fill the bottom of the steamer with water, ensuring it doesn’t touch the tamales. Cover with a towel and a lid, then steam over medium heat for approximately 1.5 hours. Check occasionally to ensure there’s enough water, and steam until the masa easily pulls away from the husks.

Once the tamales are steamed and cooked, carefully remove them from the steamer and allow them to cool slightly for 10 minutes before unwrapping. Serve your delicious beef tamales warm, alongside salsa or sour cream for added richness!