Heat the oil in a pan on medium heat. Fry the steaks in it for 3-4 minutes on each side (or according to your own taste). Take out of the pan and cover and let stand warm.
Melt butter in the same pan over medium heat. Gently fry the mushrooms and garlic for 2 minutes. Add the stock and tomato paste. Loosen the roasting set from the bottom by stirring. Let it simmer for 1-2 minutes, then stir in the cream. Simmer and thicken for 1 minute. Season to taste with salt and pepper. Pour the sauce over the steaks.
This goes well with new potatoes and green butter beans.