To prepare salsa, discard husks and stems from tomatillos. Place tomatillos and corn on a grill rack coated with cooking spray; grill 10 minutes or until browned, turning tomatillos and corn occasionally. Place tomatillos in a food processor; process until smooth. Cut kernels from ear of corn. Combine tomatillo puree, corn, onion, and next 6 ingredients (through garlic) in a medium bowl; gently stir in avocado just before serving.
To prepare pork, sprinkle pork with 1 teaspoon black pepper and 1/2 teaspoon salt. Place pork on grill rack coated with cooking spray; grill 5 minutes on each side or until done. Serve pork with salsa.