Tacos Volcánes al Pastor (Mexican Pork Tacos with Oaxaca and Chiles)

In northern Mexico, this taco is called a vampiro because the crunchy fried tortilla looks like a vampire bat wing. Down south, it's volcán - maybe since they see more volcanoes than bats. Either way, juicy pork al pastor and oozy quesillo are a brilliant combo. Thinly slicing the pork and cooking it with plenty of marinade still clinging in a hot skillet yields the charred edges and deep flavour of traditional spit-roasted pastor.

1 (2 lb) pork shoulder (Boston butt), skinless, boneless
7 guajillo chiles, seeds removed
3 morita chiles, seeds removed
4 cloves garlic
⅓ cup orange juice, freshly squeezed
¼ cup lime juice, freshly squeezed
3 Tbsp. achiote (annatto) paste
1 Tbsp. sea salt
8 (6") corn tortillas
4 Tbsp. extra-virgin olive oil
12 oz quesillo (Oaxaca cheese), coarsely grated

To Serve:
sliced onions
chopped cilantro
lime wedges

Place pork shoulder on a parchment-lined rimmed baking sheet and freeze, uncovered, until almost completely frozen, about 2 hours. Using a very sharp knife, thinly slice pork (shoot for about ⅛" thick). Transfer to a large bowl.

Meanwhile, bring guajillo and morita chiles and 1 cup water to a boil in a medium saucepan. Cover, remove from heat, and let sit 30 minutes to allow chiles to soften.

Transfer chiles and soaking liquid to a blender. Add garlic, orange juice, lime juice, achiote paste, and salt; purée until smooth. Pour over pork and toss to coat. Cover and let sit at room temperature 2 hours, or chill up to 6 hours.

Preheat to 350°F (180°C, Gas Mark 4). Place a rack in middle of oven. Evenly space out tortillas on a baking sheet and bake until lightly toasted and very crisp (edges will curl and pucker), 35-45 minutes.

Heat 1 Tbsp. oil in a large nonstick skillet over high until smoking. Spread about one-fourth of pork across skillet in a single layer; cook, undisturbed, until browned underneath, about 2 minutes. Turn over and cook, undisturbed, until browned underneath and cooked through, about 2 minutes. Transfer to a platter and wipe out skillet. Working in 3 batches, repeat process with remaining pork and 3 Tbsp. oil.

Increase oven temperature to 500°F (260°C/240°C fan, Gas Mark 10). Divide pork among tostadas and top with quesillo; bake until cheese is melted, 8-10 minutes.

Top with onion and cilantro and serve with lime wedges.