Preheat the oven to 350 degrees.

Heat a tablespoon of olive oil over medium-high heat in a skillet.

Add the diced onion to the skillet and cook for 2-3 minutes until the onions begin to soften and brown.

Mix in the minced garlic for 30 seconds.

Toss in 3 cups of baby spinach, and stir to coat the spinach in the oil. Cook until the spinach has just wilted.

Remove the onion mixture from the stove and allow to cool for a few minutes.

In a small mixing bowl, combine the crumbled feta cheese and the pine nuts.

Add in the onion and spinach mixture, and stir to combine the ingredients well. This will be your filling for the steak.

Cut rectangular pieces of flank steak that are about 3 inches by 5 inches long. Slice each piece of steak in half lengthwise, so that you split it into two separate 3x5 pieces of thin flank steak.

Place some filling along the top of each piece of steak. Carefully roll the steak away from you with the filling wrapped inside. Secure the steak roll closed with some butcher’s twine or cotton string.

Place the steaks on a baking rack or baking sheet, and place in the oven for 30 minutes or until the steak is cooked to your desired temperature.

Enjoy!