This was the first recipe I made out of the Martha Stewart Cooking School Cookbook. I have actually made this 3-4 times and it is excellent. I made it again last weekend and it is delicious!
You start out pan searing a thinner steak. Martha has a video on her blog showing exactly how to pan sear. It's easy and excellent especially when it's too cold to grill.
After that you deglaze the pan with some white wine scraping up the brown bits. You then add mustard and cream and the sauce is done. It's excellent and very easy. The recipe for Mustard Cream Sauce is here.
I highly recommend this recipe. It would be great for entertaining too.
The first time I made this I served french fries with it and it was excellent.