This Mexican recipe is extra hot. The dried guajillo chilies pack a lot of heat and give an authentic spiciness to the pineapple and pork filling. Serve in warm corn tortillas with onion, cilantro, and sour cream.
Drain pineapple, reserving juice. Place juice in a small saucepan with 1/2 cup water. Bring to a boil; add chilies. Let soak 30 minutes.
Remove stems from softened chilies, then pour chilies and liquid into a blender or food processor. Add 3/4 cup of the pineapple chunks, the garlic, oregano, cumin, salt and vinegar. Puree until smooth.
Slice pork in half horizontally, then chop into small pieces. Place in a shallow glass dish or resealable bag and add chile-pineapple mixture. Cover with plastic wrap or seal bag and marinate in refrigerator at least 1 hour or overnight. Meanwhile, dice remaining pineapple pieces. Refrigerate for later.
Heat oil in a large nonstick skillet over high heat. Scoop pork pieces from the marinade with a slotted spoon and add to pan. Discard marinade. Cook pork for 3 minutes. Add reserved pineapple pieces and cornstarch-water mixture. Cook 1 minute, until pork is cooked through and sauce is thick. Serve mixture in warm corn tortillas, topped with onion, cilantro and sour cream.