Spray 4- to 5-quart slow cooker with cooking spray. Place onion in slow cooker. In small bowl, mix dried minced garlic, cumin, pepper, salt and 2 tablespoons of the lime juice to form paste. Pat mixture on top and sides of pork roast (if roast comes tied or in netting, remove before rubbing with spice mixture). Place roast on onion. Top with chiles. Pour enchilada sauce around roast.
Cover; cook on Low heat setting 9 to 10 hours or until meat is tender.
Remove pork; when cool enough to handle, shred with 2 forks. Return meat to slow cooker; stir in cilantro and remaining 2 tablespoons lime juice. Heat tortillas as directed on package. With slotted spoon, spoon 2/3 cup pork mixture on each tortilla. Serve with salsa.