2 guajillo chilies, stemmed and seeded (See Note)
2 pork tenderloins (about 1 pound each)
1 tablespoon white vinegar
1 teaspoon dried Mexican oregano
2 tablespoons extra-virgin olive oil, plus more for coating the pan
1 teaspoon salt
1/2 teaspoon freshly ground black pepper
16 corn tortillas
1 medium white onion, chopped
1/2 cup chopped cilantro
2 limes, cut in wedge, for serving
Bring 1 cup of water to a boil, in a dry cast-iron skillet, toast the chilies over medium-low heat for 2 minutes, until fragrant; turn them and shake the pan so they don't scorch.
Put the toasted chilies in a bowl, cover with the boiling water, and let them soak until softened and reconstituted, about 15 minutes.
Using a sharp knife, make a deep slit down the length of the tenderloins and open them up so they lay flat. With the smooth side of a mallet, pound the pork between two pieces of plastic to a 1/4-inch thickness.
Transfer to a platter.
In a blender, combine the toasted chilies, vinegar, oregano, 2 tablespoons of oil, salt, and pepper, and puree to form a paste. Rub the paste on both sides of the pork. Cover with plastic wrap and refrigerate overnight.
Preheat grill or ridged grill pan. Brush grill grates with a little oil to prevent meat from sticking. Scrape off excess chili paste from pork and grill for 2 minutes per side. Remove to cutting board and let rest for 2 minutes. Slice into 1/4-inch pieces. Heat a large dry skillet over a medium flame. Warm the tortillas for 30 seconds on each side, until toasty and pliable.
To make the tacos, stack 2 warm tortillas, lay about 4 ounces of pork down the center, and sprinkle with some onion and cilantro. Drizzle 1 1/2 teaspoons of salsa on top of each taco and garnish with lime wedges.
Serves 4.
Note: Guajillo chili is the dried form of the fresh mirasol chili. Can be found at Latin markets
