In a medium saucepan, heat the oil. Add the garlic cloves and cook over medium high heat until nicely browned on all sides. Stir in the guajillo chiles and saute' until they start to soften up a bit, about 3-4 mintues.

Add all of the spices to the pan, stirring until they become fragrant, about a minute.

Add the pineapple, orange and lime juices and the vinegar. Bring t a boil, then lower heat to simmer for a couple of minutes. remove from heat and let stand for about 5 minutes.

Transfer the mixture to a blender and puree until smooth. Add more salt if needed. Place the pork in a glass dish or a ziplock bag and pour marinade over it. Make sure the meat is coated on all sides. Cover and place in the refrigerator to marinate overnight.

Light the grill. Brush the pineapple slices and onion slices with a bit of oil and grill untill lightly charred on both side. Remove from the grill and set aside.

Remove the pork from the marinade and grill until nicely charred on both sides. About 2-3 minutes per side until cook through.

Let the meat rest for about 5 minutes. Cut the meat into thin strips, and place on a serving platter. Cut pineapple and onion into strips and place on the platter with the meat.

Serve with warm tortillas, chopped cilantro and lime wedges.