Begin by trimming and cutting your beef chuck roast into large chunks. Season well to enhance the flavor.

In a pan over medium heat, lightly toast your guajillo and ancho chilies for 1-2 minutes, just until fragrant.

Combine toasted chilies, onion, garlic, diced tomatoes, and beef broth in a blender. Blend until smooth.

In your slow cooker, add the meat, then pour the blended sauce over it. Give it a gentle stir to coat the meat.

Cover the slow cooker and set it on low for 7-8 hours, or high for about 4-5 hours. Check for doneness; meat should be tender and easily shred.

Heat a little oil in a pan over medium heat. Fry each tortilla for about 30 seconds on each side until golden and pliable.

Shred the beef and fill each tortilla with the meat. Serve them warm along with the broth for dipping!