Tenderize your steak by butterflying or splitting the meat down the center so it lays flat and then pound it with a meat pounder, or mallet.
Rub minced garlic evenly over the steak, and then sprinkle steak with salt, pepper, and red pepper flakes.
Layer the spinach, bell peppers, and feta cheese onto the steak.
Then, starting at one end, roll the steak up like a big sushi roll, making sure to pull at the ends so it doesn’t get too thick in the middle. Tie it with kitchen string every couple of inches. Season with additional salt and pepper.
Place in an 11” x 7” baking dish coated with non-fat cooking spray. Bake, uncovered, at 350° for about 45-50 minutes or until meat is tender, and until the internal temperature of the roll is at least 145 degrees F.
Remove from oven and allow it to cool for about 10 minutes before slicing it into 4, equally sized rounds.