- In a bowl of warm water, soak the chili peppers for 5 minutes to soften. Drain.
- In a pot over medium heat, soften the garlic in the oil for 2 minutes. Add the spices and cook for 30 seconds. Add the orange juice, vinegar and rehydrated chili peppers. Bring to a boil and simmer for 2 minutes. Let cool.
- In a blender, purée the mixture until smooth. Pour into an airtight container.
- In a glass dish or resealable plastic bag, combine the pork with two-thirds of the marinade. Cover and let marinate for 4 to 6 hours in the refrigerator. Set the remaining marinade aside in the refrigerator until ready to serve.
- Heat a grill pan over high heat. Oil the pan. Grill the onion slices for 2 minutes on each side. Set aside on a plate. Cook the pineapple until nicely grilled. Set aside with the onions to cool. On a work surface, coarsely chop the onion and thinly slice the pineapple. Set aside in separate bowls.
- Grill half of the pork at a time for 4 minutes on each side or until nicely golden. Season with salt.
- On a work surface, cut the fat off the meat, if desired, then stack a few pork slices at a time and finely slice. Transfer to a plate and keep warm until ready to serve.
- Place the onion, pineapple, cilantro, reserved marinade, tortillas, pork and lime wedges at the centre of the table. Let everyone around the table fill their own tacos.
Guajillo is a type of dried chili pepper common in Mexican cooking. It is available at specialty grocery stores. If unavailable, you can replace the 4 guajillo peppers in this recipe with 1 roasted and peeled bell pepper and 1 fresh chili pepper. In this case, omit step 1 of the recipe.