To begin, butterfly open your flank steak with a sharp knife.
Once your steak is butterflied, lightly salt & pepper it with a half teaspoon of each.
Spread the diced peppers over the top of the steak, leaving about an inch of space around the edges. Top this with the baby spinach.
Sprinkle with the herbed, crumbled feta cheese.
Starting at the end, along the grain of the meat, roll the steak up like you are going to make cinnamon rolls.
Tie the roll closed with kitchen twine in 1 inch increments.
Trim off the excess twine. Brush the outside of the roll with olive oil.
Salt and pepper the outside.
Heat your grill to high heat and place your steak roll on the grates.
Cook it on one side for 2 minutes and turn over.
Turn the heat off on the side with the steak and cook over indirect heat at 400 degrees for 30-40 minutes, or until it registers 135 -150 degrees internally with a thermometer – depending on how done you like your steak.
Allow your steak to rest for 10 minutes and then slice into beautiful medallions.