01 -
Dice the onions, rough chop the garlic, and prepare the ancho chiles by removing stems and seeds. Cut the chiles into 2-3 pieces for easier blending.
02 -
Preheat a skillet on high heat. Season the chuck roast with salt and pepper. Add olive oil to the pan, then sear each side of the beef for 2 minutes. Add 1 cup of beef stock to the pan to deglaze and scrape up browned bits. Transfer beef and liquid to the slow cooker.
03 -
Add onions, garlic, cilantro, tomato sauce, ancho chiles, cinnamon, cumin, paprika, salt, pepper, oregano, thyme, and bay leaves to the slow cooker. Mix well. Pour in remaining stock until the liquid covers the beef. Set slow cooker to low for 8 or 10 hours.
04 -
Once cooking is complete, transfer the beef to a cutting board. Use forks to shred the meat. Discard any string or large connective tissues. Return shredded beef to a bowl.
05 -
Remove and discard the bay leaves. Using a slotted spoon, transfer the solids (onions, garlic, and chiles) from the slow cooker to a blender. Blend until smooth, incorporating ½ cup of cooking liquid if needed. Pour the blended sauce back into the slow cooker and stir. Add ½ cup of sauce to the shredded beef and mix well.
06 -
Preheat oven to 300°F. Heat a skillet over medium-high heat and lightly spray with olive oil. Dip a tortilla into the sauce and place in the skillet. Sprinkle shredded cheese across the tortilla, then add shredded beef on one half. Fold the tortilla over and transfer to an oven sheet to keep warm.
07 -
Repeat the process for all tacos. Serve each taco with a bowl of dipping sauce for full flavor.