Preheat oven to 400°.
Sprinkle pork with oregano, salt, and crushed pepper. Heat a medium ovenproof skillet coated with cooking spray over medium- high heat. Place pork in pan; cook 2 minutes on each side or just until browned. Place pan in oven and bake, uncovered, at 400° for 15 to 18 minutes or until a meat thermometer inserted into thickest portion of pork registers 160°. Let stand 5 minutes. Thinly slice pork into 24 pieces.
Reduce oven temperature to 300°.
Spread mayonnaise evenly on bottom half of each roll. Spread mustard evenly on top half of each roll. Arrange 4 pickle slices on bottom halves of rolls; top with 4 pork slices, 1 slice ham, and 2 half slices cheese. Place tops of rolls over cheese, mustard side down. Place sandwiches on a baking sheet. Bake at 300° for 10 minutes or until cheese melts.