2 whole guajillo chiles
2 Tbs vegetable oil (for the pan)
1 tsp ground cumin
1 tsp dried Mexican oregano
1 Tbs salt
2 tsp sugar
1 Tbs achiote paste
1 chipotle chile, seeded + 2 tsp adobo sauce from can
3 cloves garlic, crushed and peeled
1/4 c vinegar
1 lime
2 lb pork loin
Rehydrate the dried chiles:
Click here for a detailed tutorial! Stem and seed the dried chiles, then sear in the oil in a hot pan for 30 seconds per side until shiny and charred. Soak in hot water for 20 to 30 minutes, making sure they are submerged. Drain the chiles before using them in the sauce.
Blend the sauce:
While chiles soak, prep the chipotle by cutting it in half and removing the seeds and flesh with a knife. Smash the garlic cloves and peel them.
You can find achiote at Latin markets in little boxes with the spices. It's primarily annatto seed - which gives it a distinctive bright red coloring - but incorporates some spices that add that umami, smoky flavor you want in dishes like this one. In a pinch, you can use ground annatto from the spice aisle, or just leave it out.
In a large waterproof blender, add rehydrated chiles, chipotle, spices, achiote, garlic, and vinegar. Blend until liquified.
Marinate the meat:
Trim as much as fat from the pork loin as you want (how much there is will depend on what cut you are using). Take a sharp knife and slice the pork as thin as you can; you want to marinade it sliced so that every bit gets the flavor and coloring. Put all the pork slices into a large bowl, and pour the sauce in over it. Mix it together with your hands (or tongs, if you want) so that every piece is covered.
Line a loaf pan with aluminum foil and using your hands (or tongs), start layering the pork slices flat so you have a loaf-shaped stack. Seal tightly with aluminum foil and let sit in the refrigerator for up to 36 hours. (You could do this after it marinades, if you want.)
Cook:
Uncover the loaf pan but leave the pork inside it. Roast in the oven at 275 for 4 hours. Cool slightly and return to the refrigerator, covered.
Remove meat from tray when it's cool, and remove any fat that has solidified around the pork. At this point, you can put the meat in the fridge until you're ready to eat - or go ahead and move to the next step.
Slice the meat again - since you're doing this the opposite way, you'll end up with small shavings of cooked, flavorful meat. Heat a skillet or large pan on the stove, and stir fry the chopped pork so that it chars - about 8 to 10 minutes on medium high. When you're ready to serve it, remove from heat and add the juice of one whole lime, and stir it in. Normally you serve al pastor tacos with lime wedges, but this makes sure the lime juice is distributed evenly and adds some liquid to the mix.
Serve the pork in corn tortillas with white onions and cilantro for authentic tacos al pastor.
