Prepare the Chilli Base: Place the deseeded guajillo, ancho, and árbol chillies in a bowl. Cover them with boiling water and let them soak for 20 minutes. You'll know they're ready when they have softened and become pliable, and the water has taken on a deep, rusty red colour.

Sear the Beef: Pat the beef chunks dry with paper towels. Heat the vegetable oil in a large, heavy-bottomed pot over medium-high heat. Working in batches to avoid overcrowding, sear the beef until all sides are a deep mahogany brown, about 4-5 minutes per batch. The sizzling sound should be vigorous, and the meat should release easily from the pan. Remove the beef and set aside.

Build the Sauce: In the same pot, add the chopped onion, garlic, and tomatoes. Cook for 5-7 minutes, stirring occasionally, until the onions become translucent and the tomatoes start to break down and release their juices. The smell will be sweet and savoury. Transfer this mixture to a blender along with the softened chillies, 120 ml of the chilli soaking water, cumin, oregano, smoked paprika, black pepper, and salt. Blend until completely smooth—the sauce should be a vibrant, brick-red colour with a thick, silky texture.

Simmer the Birria: Return the seared beef to the pot. Pour the blended chilli sauce over the meat, then add the beef stock, bay leaves, and apple cider vinegar. Stir everything together. Bring the liquid to a gentle boil, then reduce the heat to low, cover, and let it simmer. You want a lazy, occasional bubble. Cook for 2.5 to 3 hours, or until the beef is fork-tender and shreds with minimal effort. The kitchen will smell richly of toasted spices and chillies.

Shred and Defat: Once the beef is tender, remove the bay leaves. Using two forks, shred the beef directly in the pot. The meat should pull apart into long, juicy strands. If there's a layer of fat on top of the consommé, skim it off with a spoon. Taste the consommé and adjust salt if needed. The broth should be intensely savoury, with a gentle heat that lingers.

Assemble the Tacos: Heat a large frying pan or griddle over medium heat. Quickly dip a corn tortilla into the top of the consommé to lightly coat it—this is key for flavour. Place the tortilla in the hot, dry pan. Sprinkle a generous amount of shredded cheese on one half of the tortilla. Add a few tablespoons of the shredded birria beef on top of the cheese. Fold the other half over to create a half-moon shape. Cook for 2-3 minutes per side, until the tortilla is golden brown and crisp, and the cheese is melted and bubbling. The sizzle should be steady but not violent.

Serve Immediately: Transfer the finished tacos to a plate. Serve alongside small bowls of the warm consommé for dipping. Garnish with fresh coriander, diced white onion, and a squeeze of lime. The contrast between the crunchy, cheesy taco and the warm, spicy broth is everything.