Tacos Al Pastor

1 tablespoon canola oil, plus more for brushing 3 garlic cloves 1 teaspoon dried oregano 1/2 teaspoon ground cumin 1/2 teaspoon pepper 1/4 teaspoon ground cloves 4 guajillo chiles—stemmed, seeded and cut into 2-inch pieces 1/3 cup pineapple juice 1/4 cup distilled white vinegar 2 tablespoons achiote paste Sea salt 2 pounds boneless pork shoulder, sliced 1/4 inch thick 1/2 medium pineapple, peeled and sliced 1/2 inch thick 1 medium red onion, sliced crosswise 1/2 inch thick Warm corn tortillas, chopped cilantro and lime wedges, for serving