Start by preparing the chiles. Remove the stems from guajillo, ancho, and arbol chiles, shake out the seeds, and rinse them under cool water.

In a medium saucepan, combine the rinsed chiles with enough water to cover them. Bring to a gentle boil and simmer for about 15 minutes until tender.

Preheat your broiler. Place Roma tomatoes, quartered onion, and unpeeled garlic cloves on a baking sheet, broil for 4-6 minutes until charred.

In a high-powered blender, combine softened chiles, roasted vegetables, beef broth, vinegar, and spices. Blend until smooth.

In a slow cooker, place chunks of beef chuck roast. Pour the blended sauce over the meat, stir gently to coat.

Cover the slow cooker and set to cook on low for 8-9 hours or on high for 4-5 hours until beef is tender.

Remove bay leaves and shred the beef in the sauce using two forks.

Serve in deep bowls, with optional toppings like chopped onion, cilantro, and lime wedges or as filling for tacos.