Place the deseeded guajillo and ancho chiles in a heatproof bowl. Pour enough boiling water over them to fully submerge. Let them rehydrate for 15-20 minutes, or until softened. Drain, reserving about 1/2 cup of the soaking liquid.

Pat the beef chuck roast pieces dry with paper towels. Season generously all over with 1 tsp salt and 1/2 tsp black pepper.

Heat the olive oil in a large Dutch oven over medium-high heat. Once hot, add the beef pieces (you may need to do this in batches to avoid overcrowding) and sear for 3-5 minutes per side, until deeply browned. Remove the beef from the Dutch oven and set aside.

Reduce heat to medium. Add the chopped white onion to the Dutch oven and sauté for 5-7 minutes, scraping up any browned bits from the bottom, until softened and translucent. Add the minced garlic and cook for another minute until fragrant.

In a blender, combine the rehydrated guajillo and ancho chiles, the chipotle pepper (if using), diced tomatoes (undrained), tomato paste, 1 cup of beef broth, ground cumin, Mexican oregano, and apple cider vinegar. Blend until completely smooth. If the sauce is too thick to blend, add a little of the reserved chile soaking liquid.

Pour the blended chile sauce into the Dutch oven with the sautéed onions and garlic. Stir in the remaining 2 cups of beef broth and the bay leaf. Bring the sauce to a gentle simmer.

Return the seared beef pieces to the Dutch oven, ensuring they are mostly submerged in the sauce. Cover the Dutch oven tightly with its lid.

Transfer the Dutch oven to a preheated oven at 300°F (150°C) and cook for 3 to 3.5 hours, or until the beef is incredibly tender and easily pulls apart with a fork.

Carefully remove the Dutch oven from the oven. Take out the beef pieces and place them on a cutting board or shallow dish. Remove and discard the bay leaf from the sauce. Using two forks, shred the beef into desired consistency.

Return the shredded beef to the sauce in the Dutch oven. Stir well to coat all the beef with the rich sauce. Taste and adjust seasoning with additional salt and pepper if needed.

Serve hot as filling for tacos, burritos, quesadillas, tostadas, or as a hearty bowl with rice and beans. Garnish with fresh cilantro, pickled onions, or a squeeze of lime.