Seared Flank Steak with Shallot-Mustard Sauce

I keep every copy of my Fine Cooking magazines because each issue is loaded with amazing recipes. This is one of my all time favorites. Just a couple of quick notes. We always double the sauce, because I’m a saucy girl. Second I don’t know what kind of super powered oven they use but the timing is a little off on this unless you want your steak rare. For best results use a meat thermometer. Medium rare is 130 – 135 F and medium is 140 -145 F. For flank steak I wouldn’t recommend anything over medium.

Seared Flank Steak with Shallot-Mustard Sauce

1 flank steak, about 1-1/2 lb.
Kosher salt and freshly ground black pepper
1 Tbs. corn oil
6 Tbs. cold unsalted butter (4 Tbs. cut into 1/2-inch cubes)
3 Tbs. finely minced shallot
3 medium cloves garlic, minced
1/2 cup dry red wine
3/4 cup low-salt beef broth
1 tsp. chopped fresh thyme
1 tsp. Dijon mustard
1 Tbs. chopped fresh tarragon

Set a rack in the center of the oven and heat the oven to 400°F. Season the steak generously with salt and pepper. Heat an ovenproof 12-inch sauté pan over high heat until very hot. Add the oil to coat the pan and sear the steak on one side until well browned, about 1-1/2 minutes. Flip with tongs and cook until the second side is well browned, about another 2 minutes. Put the pan in the oven and roast until the steak is cooked to your liking, 5 to 7 minutes for medium rare. Transfer the steak to a cutting board and let rest, lightly covered with foil, while you make the sauce.

Set the same skillet over medium heat and add 2 Tbs. of the butter. When the butter melts, add the shallot and garlic and cook until soft and translucent but not browned, about 2 minutes. Add the wine, increase the heat to medium high, and boil until syrupy, 2 to 4 minutes. Add the broth and thyme and boil until about 1/3 cup of liquid remains, 6 to 8 minutes. Reduce the heat to low and whisk in the mustard. (Don’t let the sauce boil after the mustard is added.) Stir in the 4 Tbs. butter cubes, a few at a time. Stir in half the tarragon and season the sauce to taste with salt and pepper.

With a sharp knife, slice the steak thinly across the grain on the diagonal, drizzle with the sauce, and sprinkle with remaining tarragon.