For Christmas Dinner, we got a big tenderloin from Costco. I trimmed it and carved it up, a la Alton Brown, and roasted the center cut.
I have a huge butt end roast left over, 3 nice petit filet mignons, and some tenderloin tips that will make great kebabs or stirfry some day. I made it Alton's method, except I rolled mine in Montreal Steak Seasoning, fresh chopped thyme and oregano, and extra pepper. He has you sear it, then rest 10 minutes, then bake at a mild 250 until it reaches 135 in the middle. Then it rests 30 minutes, great for letting it get nice and juicy, and plenty of time for me to make a sauce and do last minute prep on the meal.
For my sauce, I sauteed about 1/4 cup finely chopped onion and 1 minced garlic clove in some butter in the same cast iron pan I seared and roasted the meat in. Then, I deglazed the pan with 1 cup red wine and 1/2 cup super concentrated stock (from the Greenburg turkey). I let this reduce by about 75%, thickened w/ a little cornstarch, then added a few tablespoons of cream and some cracks of black pepper.
I actually took my roast to 138, but next time I'll go to 140, since my audience prefers medium-well more than medium. (Not Colin! "I like the red part!" he says.) The beef was SO tender and buttery, and the sauce put it over the top. I can't wait to eat the rest of it!