Preheat grill to medium heat. Pierce meat several times with fork; place in resealable plastic bag.
Mix dressing and mustard; pour over meat. Seal bag; turn over several times to evenly coat meat with dressing mixture. Refrigerate 15 min. to marinate.
Drain; discard bag and marinade.
Thread meat onto six skewers alternately with the peppers.
Grill 8 to 10 min. on each side or until meat is cooked through.