Combine first 5 ingredients in a small bowl. Rub mixture over pork. Insert a meat thermometer into thickest part of tenderloin, if desired.
Place tenderloins on grill rack coated with cooking spray; cover and grill 20 minutes or until meat thermometer registers 160°, turning occasionally.
Combine pineapple juice, cornstarch, and mustard in a small saucepan, stirring well with a whisk. Bring to a boil over medium heat. Cook, stirring constantly, 2 minutes or until thick.
Let pork stand 10 minutes before cutting into thin slices; serve pork with pineapple sauce.