In a 4- to 6 quart slow cooker combine the salsa, chili powder, oregano, cocoa and 1 teaspoon salt. Add the pork and turn to coat.
Cook, covered, until the meat is tender and pulls apart easily, on high for 4 to 5 hours or on low for 7 to 8 hours.
Using two forks, shred the pork and stir it into the cooking liquid. Serve with tortillas, cilantro, sour cream, lime and extra salsa.