6. Grill the slices of Italian bread on both sides until toasted, taking care to not let it burn.

7. To assemble the sandwiches, spread the Horseradish Aioli on 4 pieces of bread. Arrange the sliced steak on top, then cover with the pickled onions and arugula. Finish the sandwich with the remaining toast and slice in half. Serve warm.

Serves 4