Heat grill to medium-high. Rub both sides of steak with olive oil and sprinkle with salt and pepper. Cook steak for about 8 minutes per side. Grill onions along side with steak. Let flank steak cool for 5 minutes before thinly slicing on the diagonal. Warm flat bread on the grill for 2 minutes each side, if desired.
In large bowl, toss salad greens with Marie’s Buttermilk Ranch Dressing. Top each flat bread with sliced steak, onions, salad greens and feta cheese to serve.
Tip: Have Marie’s Buttermilk Ranch handy for an extra pour!