mashed potatoes, roasted mushrooms and peppercorn sauce, to serve
Preheat oven to 200°C. Season the steaks with celery salt and rub well. Arrange pairs of prosciutto overlapping end on end, then scatter with sage leaves. Place a steak on the near edge of each, then roll up securely.
Drizzle the steaks with half the oil, then cook on a hot ribbed griddle, turning regularly until browned. Transfer to a roasting pan and bake for 15 minutes, until medium-rare.
Toss the asparagus in the remaining oil and season generously with salt and pepper, then cook on the griddle for 3 minutes, turning several times. Carve the steaks and serve with the asparagus, mashed potatoes, mushrooms and peppercorn sauce.