Marchand de vin sauce is a classic French reduction of red wine and rich veal stock, or demi-glace, the latter taking several hours to make!
This is a far simpler version of the sauce using bought beef stock, or even a half a beef stock cube dissolved in hot water!
Season fillet steaks with a little sea salt and plenty of coarsely ground black pepper, and sear on both sides in hot olive oil,
until cooked to your liking. Remove to a warm plate, cover with some kitchen foil and keep warm while you finish the sauce.
Add a finely chopped shallot to the pan and fry for a couple of minutes until softened. Season well with plenty of freshly ground black pepper,
then add a glass of red wine and a similar amount of beef stock and cook down to a syrupy sauce, adding any juices from the steaks.
Transfer the steaks to warm plates, then strain the sauce through a sieve and pour over the steaks. Served here with new potatoes and asparagus.