With a meat mallet, pound the steaks to about 1/4 inch thick. Sprinkle with a little pepper. Arrange peppers and onions horizontally on the steaks.
Starting at the narrow end of each steak roll up jelly roll style and tie with the butcher twine. Place in a shallow dish and pour half of the teriyaki sauce over the rolled up steak. Cover and place in Fridge for 2 hours.
To Grill: After marination time is up, grill on medium heat. You want to brush the rolls with the rest of the teriyaki sauce. turn once to get nice grill marks. Before serving use kitchen knife to remove the string.