How to make
Wash and dry the steaks, pound them lightly with a mallet and place them in a bowl. Sprinkle with black pepper to taste and add the soy sauce and mustard, rub them well and set them aside.
Cut the onion and mushrooms into strips.
Heat a little oil and fry the onions first, until soft, then the mushrooms until they acquire a light golden color, salt the fried vegetables and set them aside.
Heat a little oil and fry the steaks on both sides until golden. Remove them from the pan and arrange them on the bottom of a tray.
Melt and heat the butter, add the flour and fry until golden.
Pour the cold milk in a thin stream while stirring continuously and cook until it has thickened. Add salt and black pepper to taste.
Pour the béchamel over the steaks, sprinkle the onions and mushrooms evenly over it.
Place the tray in an oven preheated to 360°F (180°C) and bake for about 30 minutes. Sprinkle with grated yellow cheese evenly and bake for another 15 minutes until golden brown.
Remove the tray from the oven and sprinkle with finely chopped parsley.
The oven-baked steaks with mushrooms and béchamel sauce are very tasty.