Heat a dry skillet over medium heat. Toast guajillo and pasilla/ancho chilies 20–30 seconds per side until fragrant but not burned. Transfer to a bowl and cover with 2 cups of very hot water. Let soak 20 minutes until soft. Reserve soaking liquid.

Make chile-tomato purée

Drain chilies, reserving 1 cup of soaking liquid. In a blender, combine rehydrated chilies, roma tomatoes, quartered onion, garlic cloves, apple cider vinegar, oregano, cumin, and 1/2 cup of the reserved soaking liquid. Blend until smooth, adding up to the reserved soaking liquid to reach a thick sauce consistency (about 1/2–1 cup). Strain through a fine-mesh sieve into a bowl to remove bits — set aside.

Season and sear pork

Pat pork pieces dry. Season all over with 1 tbsp kosher salt (of the 1.5 tbsp) and 1 tsp black pepper. Heat a large Dutch oven over medium-high heat and add 2 tbsp vegetable oil. Sear pork in batches, 3–4 minutes per side, until well browned. Transfer seared pork to a plate; discard excess fat leaving about 1 tbsp in the pot.

Deglaze and braise

Lower heat to medium. Add the chile-tomato purée to the pot and cook 2–3 minutes, stirring, until fragrant. Add the seared pork back to the pot, pour in 2 cups pork stock, add bay leaf and remaining 1/2 tbsp salt. Bring to a simmer, then cover and transfer to a 325°F (160°C) oven, or continue simmering on the stovetop at low heat. Braise for 2.5–3 hours, or until meat is fork-tender and pulls apart easily.

Shred and crisp (del bac classic finish)

Remove pork from the braising liquid and let rest 10 minutes. Shred pork with two forks, discarding any large amounts of fat or bone. Strain and reserve the braising liquid. If you want the Del Bac 'crisped' texture, heat a skillet over medium-high with 1–2 tbs lard or oil. Add shredded pork in an even layer and let brown without stirring for 2–3 minutes, then stir and brown additional spots until edges are crisped and caramelized. Keep warm.

Finishing Sauce (optional)

Place 1 cup reserved braising liquid in a small saucepan over medium heat. Simmer until slightly reduced (5–8 minutes). Whisk in 1 tbsp unsalted butter, 1 tbsp lime juice, and 1/2 tsp honey. Taste and adjust seasoning with salt. Spoon a few tablespoons over shredded pork before serving, reserving some sauce for guests.

Corn Tortillas & Assembly

Warm and char tortillas

To warm: heat a cast-iron skillet or comal over medium-high. Lightly brush each tortilla with a thin film of lard or oil (about 1/2 tsp each) and place on the hot surface. Cook 20–30 seconds per side until warmed and slightly blistered; move tortillas to a towel to keep warm and pliable. Alternatively, briefly char them directly over a gas flame for smoky edges.

Assemble tacos

Place 2 warmed tortillas on a plate. Add about 3 oz (1/4 cup) of shredded, crisped pork per taco (approximately 12 tacos from 3 lbs pork). Top with a pinch of diced white onion and chopped cilantro. Add a small squeeze of lime and a few flakes of coarse sea salt. Serve extra finishing sauce on the side.

Serve

Serve immediately while tortillas are warm and pork is juicy with crisped edges. Provide extra lime wedges, hot sauce, and pickled onions if desired.