Place the flank steak between two sheets of plastic wrap and pound evenly to about ½ inch thickness.

In a mixing bowl, combine spinach, ricotta, mozzarella, garlic, salt, pepper, and Italian seasoning until well blended.

Spread the filling evenly over the flank steak, leaving a small border. Roll tightly and secure with toothpicks or twine.

Heat olive oil in a skillet over medium-high heat and sear the pinwheels for 3-4 minutes on each side until golden brown.

Drizzle balsamic vinegar over the pinwheels, then bake in a preheated oven at 375°F for 20-25 minutes until cooked to medium-rare.

Allow to rest for 5-10 minutes before slicing into 1-inch thick pieces and serve warm.