Tenderize the steaks. Squeeze lemon juice over them, sprinkle with salt and pepper. You can pour a little white wine over them as well. Cover and leave to marinate for 2 hours.
Then, transfer the pork into a greased oven dish, distribute the cleaned mushrooms on top of the meat, pour in some water and wine, then a little salt and pepper.
Cover the oven dish tightly with foil and set it to bake for 2 hours on a moderate oven setting. Thicken the steak sauce with the potato puree and serve with the meat and mushrooms.