Place 40g of the butter and stock in a saucepan over medium heat and bring to the boil. Gradually whisk in the polenta and cook, stirring, for 2–3 minutes or until thickened. Remove from the heat and stir through the parmesan. Set aside and keep warm.
Melt the remaining butter in a large non-stick frying pan over high heat. Add the steaks, sage, garlic and lemon and cook for 1–2 minutes each side for medium or until cooked to your liking. Top the polenta with the steaks and spoon over the pan juices to serve. Serves 4