Bring a small pot of water up to a boil over high heat and remove from the heat. Put the guajillo peppers in the water, making sure that they’re fully submerged. Let soak for 10-15 minutes, or until very soft. Remove from the water, pull off the stems, open and deseed.
Place the peppers, garlic, adobo, rice vinegar, sugar, and salt in a blender and blend until smooth. Use to marinate meats or fish.
Marinate the drumsticks in al pastor sauce for 30 minutes or overnight.
Heat the oven to 375°F and bake with half the pineapples for 45 minutes until cooked through (160°F). Turn the oven on broil and crisp up for 2-3 minutes, checking often.
Top with remaining pineapples, thinly sliced onions, and cilantro. Serve as is, with lime, or shred and serve with warmed tortillas.
