Step 1

Remove the stems from the guajillo and ancho peppers and remove the seeds. Place the dried chiles in a large bowl and cover with very hot or boiling water. Soak them for 15 minutes, or until they become very soft and rehydrate. Drain and discard the water. Add them to a food processor and process until smooth.

Step 2

Add the beef chunks to a bowl. Add the ancho-guajillo paste and toss to even coat.

Step 3

Heat the oil in a large cast iron pan to medium-high heat. Sear the beef chunks a few minutes per side to get a nice coating. Transfer to a slow cooker or crock pot.

Step 4

Deglaze the pan with a bit of beef stock, water or wine and scrape all of the brown bits from the bottom of the pan. Pour it into the crock pot.

Step 5

Add the chipotles in adobo, beef stock, vinegar, lime juice, onion, garlic, oregano, cumin, bay leaf and salt and pepper to taste. Stir.

Step 6

Cook on high for 4 hours, or on low for 6-8 hours, or until the beef is fork tender. It should easily break apart with a fork. It could take a bit longer to cook, depending on your slow cooker.

Step 7

Shred the beef with 2 forks and serve as desired.