Remove stems and seeds from the guajillo and ancho peppers. Tear them open.

Toast the peppers in a dry skillet over medium heat for 20–30 seconds per side until fragrant. Watch closely to avoid burning.

Transfer toasted peppers to a bowl and cover with hot water. Soak for 20 minutes until pliable.

Drain peppers, reserving about 1/2 cup of the soaking liquid.

In a blender, combine the soaked peppers, garlic, cumin, oregano, a pinch of salt, and some black pepper. Add 2–3 tablespoons of the reserved soaking liquid and blend to a smooth paste, adding more liquid if needed.

Place the beef chuck roast into the crockpot. Scatter the diced onion and the bay leaf around it.

Pour the pepper paste over the roast, then add the beef broth. Gently nudge the roast to ensure it’s mostly submerged in liquid.

Cook on low for 8 hours (or high for 4–5 hours) until the meat is falling-apart tender.

Remove the roast to a cutting board, shred the beef with two forks, and discard excess fat and the bay leaf.

Return the shredded beef to the crockpot and stir into the consomé to soak up flavor.

Warm corn tortillas on a dry skillet or directly over a gas flame until soft and slightly charred.

Build tacos by filling each tortilla with shredded birria, topped with chopped onion and cilantro, and a squeeze of fresh lime. Serve warm consomé on the side for dipping.