In small bowl, mix honey, mustard and horseradish; set aside. Rub pork with 1 tablespoon vegetable oil, the salt and pepper. Place pork on grill over medium heat. Cover grill; cook 15 minutes. Turn; generously brush with honey mustard mixture, and grill 8 to 13 minutes longer or until pork has slight blush of pink in centre and meat thermometre inserted in centre reads 145°F. Transfer to cutting board; cover with foil and let stand 5 minutes. Thinly slice.