Remove stems and seeds from guajillo and ancho chilies. Rinse briefly. Place chilies in a bowl and cover with hot water; soak 15 minutes until softened, then drain, reserving a little soaking liquid.

Make marinade

In a blender add soaked chilies, achiote paste, pineapple juice, orange juice, white vinegar, garlic, cumin, oregano, smoked paprika, salt and pepper. Blend until completely smooth. If too thick, add 1–2 tbs of the reserved chili soaking liquid or water to reach a saucy consistency.

Marinate pork

Place sliced pork shoulder in a bowl or resealable bag. Pour the marinade over the pork, rubbing it into pieces so all surfaces are coated. Cover and refrigerate at least 4 hours, ideally overnight (8–12 hours) for best flavor.

Cook pork

Preheat a grill or cast-iron skillet over medium-high heat. Lightly oil the surface. Remove pork from marinade, letting excess drip off. Grill or sear in batches for 3–4 minutes per side until caramelized and cooked through (internal temperature ~145–160°F / 63–71°C depending on desired doneness). Transfer to a cutting board and let rest 5 minutes, then chop into small bite-sized pieces.

Grill pineapple (optional)

Brush pineapple slices with 1 tbs oil and grill until char marks appear, about 1–2 minutes per side. Chop into small pieces and reserve to top tacos.

Pickled Red Onions & Salsa Verde

Quick pickled onions

In a small saucepan combine 1/2 cup white vinegar, 1/2 cup water, 1 tsp sugar and 1/2 tsp salt. Bring to a simmer to dissolve sugar and salt. Place sliced red onions in a heatproof jar or bowl and pour the hot brine over them. Let cool to room temperature, then cover and refrigerate at least 30 minutes (best 1–2 hours).

Make salsa verde

Place husked tomatillos and serrano (stem removed) on a hot dry skillet or comal. Roast, turning, until charred and softened, about 6–8 minutes. Transfer to blender along with cilantro, lime juice, 1/2 tsp salt and 2 tbs water if needed. Blend to a coarse-smooth sauce. Taste and adjust salt or lime. Chill briefly or use immediately.

Assembly & Garnishes

Warm the corn tortillas on a dry skillet or directly over a low flame until pliable and lightly charred, keep wrapped in a clean towel to stay warm.

To assemble each taco: place 2 warmed tortillas on a plate. Add about 2–3 oz (roughly 1/4 cup) chopped al pastor pork per taco (use more for heartier servings). Top with a spoonful of grilled pineapple pieces, a few pickled red onion slices, a drizzle of salsa verde, a sprinkle of crumbled cotija, and chopped cilantro. Add thin radish slices if using and a squeeze of lime. Finish with hot sauce to taste.

Serve immediately with remaining salsa verde, lime wedges and pickled onions on the side.