Wash the potatoes, cut them up and steam until they are firm to the bite. Fry in a little olive oil and butter before serving. Cut the onions into fine strips and brown them well in olive oil. Add the garlic clove and bay leaf and souse with the red wine, let the wine evaporate, pour in the gravy and reduce briefly.
Cut the meat into 150 g slices, tenderise, dust with flour and sear on both sides in a pan with oil. Souse with red wine and pour the onion sauce over. Serve with the potatoes.
Tip: if you are hosting more than 6 people, the entrecote can also be prepared as a whole item, cooking for around 30 minutes per kilo of meat at 180°C in a fan oven.