How to Make It
In a medium saucepan, heat the 1 tablespoon of oil. Add the garlic and cook over moderately high heat, turning occasionally, until lightly browned, about 1 minute. Stir in the oregano, cumin, pepper and cloves and cook until fragrant, about 1 minute. Add the chiles and cook, stirring, until blistered in spots, about 30 seconds. Add the pineapple juice, vinegar and achiote paste and bring to a boil. Remove from the heat and let stand for 5 minutes.
Transfer the chile mixture to a blender and puree until smooth. Season with salt. Scrape the marinade into a large, sturdy plastic bag. Add the pork and turn to coat. Set the bag in a small baking dish and refrigerate overnight.
Light a grill or preheat a grill pan. Brush the pineapple and onion with oil. Grill over high heat, turning once, until lightly charred and softened, 3 to 5 minutes. Transfer to a carving board and tent with foil.
Remove the pork from the marinade. Grill over high heat until lightly charred and just cooked through, 2 to 4 minutes. Transfer to the carving board and let rest for 5 minutes.
Cut the pineapple, onion and pork into thin strips and transfer to a bowl. Season with salt. Serve with corn tortillas, chopped cilantro and lime wedges.