My boyfriend cooked this the first time he cooked a meal for me. He followed it up with Bananas Foster, something else I crave on a regular basis. We added the mushrooms to the classic sauce.
2 steaks (about 1 1/2" thick)
1 tablespoon olive oil
5 tablespoons butter
1 lb mushrooms, thickly sliced
1 cup green onions, sliced
1/2 Cup brandy
1 1/2 tablespoon dijon mustard
2 teaspoons worchestershire sauce
juice of one lemon
1 cup beef broth
Pan-fry the two steaks over medium-high heat in the olive oil for about five minutes per side for medium-rare. Remove steaks from pan and put in warm oven. Drain off excess fat from pan, add a tablespoon of the butter, and saute the mushrooms over medium heat until just brown.
Add two tablespoons butter to pan and saute the green onions over medium-high heat until soft (about one minute) and then add the brandy, mustard, lemon juice, worchestershire sauce, and beef broth to the pan and simmer. Remove pan from heat and stir in the remaining butter.
Serve the steaks pre-sliced and generously spoon the sauce over the steaks. Goes well with wild rice.
 Isn't that sweet? His usual 'good impression dish' is grilled shrimp, but I can't eat that. He improvised.
 Unsalted butter. I keep it in the freezer when I find it on sale.
 I said I liked mushrooms, right?
 Either Grey Poupon or a good stone-ground mustard work well, but that's a matter of taste. If, when the sauce is tasted, the mustard flavor is non-existant, add more.
 And a little longer for medium. And, of course, if the steaks are thinner, it'll take less time.
 A 'warm oven' is set at about 200F. Sometimes I just stack the stuff in the microwave.
 Adding cold butter to a warm sauce is a process called 'mounting', which makes me think of UNIX and hard drives.