Combine oil, lemon juice and dry salad dressing mix. Pour over beef cubes in shallow dish. Cover and refrigerate 1 hour or longer. Thread beef cubes, green peppers and onion alternately onto skewers. Grill kabobs on uncovered grill about 15 minutes, brushing often with marinade and turning to brown all sides. Add cherry tomatoes to ends of skewers just a few minutes before serving.