In a small bowl, whisk together soy sauce, Truvia, vinegar and pineapple juice. Put steak pieces in a gallon-sized resealable bag and pour marinade over the steak.
Seal and let marinate in the refrigerator for at least 2 hours. If using wooden skewers, soak in water for 30 minutes before cooking.
Oil and preheat grill to medium-high heat. Discard marinade then thread steak, pineapple, peppers and onion onto skewers.
Grill kabobs for 2-3 minutes on each side, or until steak reaches desired doneness and vegetables are tender. Remove from grill and serve.