1)       Butterfly the flank steak with the grain. Place together with the balsamic vinegar in a baking dish, cover with plastic wrap for 30 minutes in the fridge.

2)       Put the walnuts in a foodprocessor together with half of the parmesan, garlic, red pepper flakes, cornmeal. Blend while slowly adding the olive oil.

3)        Preheat the oven to 230 degrees Celsius. Take the flank from the fridge, pat dry and place on a cutting board. Spread a layer of the walnut paste, arugula and sun-dried tomatoes. Roll and tie up with butcher twine. Season the exterior with the remaining parmesan, salt, rosemary and pepper. Place the roulade on a rack uncovered.

4)       Roast in the oven at 230 degrees the roulade for 10 minutes, lower heat to 165 degrees Celsius and keep the roast in for another 60 minutes. Take out the roast which should be medium rare, allow the roast to rest for 10 minutes before slicing.