Cut pork tenderloin into 1-inch (2.5 cm) cubes; place in bowl. Add olive oil, lemon rind lemon juice, oregano, garlic, salt and pepper. Thread onto 8 metal skewers. Place on greased grill over medium-high heat; brush with any remaining marinade. Close lid and grill, turning once, until just a hint of pink remains inside, 10 minutes.