In a bowl, stir together orange juice, tomato paste, chile pepper and adobo seasoning. Set aside.

Spray inside your slow cooker with cooking spray. Place pork shoulder in slow cooker. Pour orange juice mixture over pork. Cover; cook on LOW 8 hours or on HIGH 4 hours or until pork is tender.

While pork shoulder cooks, combine drained tomatoes, onion and cilantro in small bowl; cover and refrigerate.

Remove pork from slow cooker; pull apart to shred. Return to slow cooker; stir.

Divide pork evenly between tortillas. Top each with tomato mixture. Add your choice of shredded cheese, if desired.