Seared Flank Steak with 'stop me before I drink this' Shallot-Mustard Sauce

I love flank steak. It is so easy to cook and can be prepared in so many different ways that it never feels like the same meal twice. Last Sunday we had Seared Flank Steak with Shallot-Mustard Sauce served with Roasted Sweet Potatoes with Apples and Maple-Sage Butter. Both recipes are from Fine Cooking and both are dishes I would definitely enjoy again. We were particularly enamoured with the Shallot-Mustard sauce. It came together as the last part of the meal and while I was reducing and whisking, simmering but not boiling I thought to myself 'Do we really need sauce? I bet the steak will be just fine without it.'. Man, was I wrong. Not totally wrong. The steak would have been fine with no sauce. But the sauce (which, if I'm being honest is mostly butter) made the meal. As the title of this post suggests.

I need to work on figuring out how to take better pictures in low-light situations. Sunday dinner shots are usually taken in low-light and they are consistently blurry. This steak tasted so good I feel like this picture doesn't do it justice.

I don't know why I was so surprised that this steak was so good. Last Summer I discovered the taste sensation that results from topping grilled steaks with pats of butter. This shallot-mustard sauce features six tablespoons of butter. Lesson learned. Butter does indeed make everything better. Our plates were shiny at the end of this meal from mopping up every last drop of delightful sauce.  The Sweet Potato Apple side dish was a nice sweet accompaniment to the more savoury steak, although my timing was a bit off so rather than crisp sweet potato wedges ours were a bit mushy. Which worked out well when it came time for leftovers the next day as I simply mashed the apples and sweet potatoes together for a nice side dish with some baked chicken breasts. There were no steak leftovers. See above - buttery sauce too good to resist!

Seared Flank Steak with Shallot-Mustard Sauce - from Fine Cooking

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.

Roasted Sweet Potatoes with Apples and Maple-Sage Butter - from Fine Cooking

1-1/2 to 2 lb. sweet potatoes, peeled, halved crosswise, and cut into 3/4-inch-thick wedges
2 Tbs. olive oil
Kosher salt and freshly ground black pepper
2 Tbs. unsalted butter
1 medium-large tart green or red apple, quartered, cored, cut into 16 wedges, wedges halved crosswise
1 Tbs. chopped fresh sage
1-1/2 tsp. fresh lemon juice
1 tsp. pure maple syrup  

Position a rack in the top third of the oven and heat the oven to 475°F.

In a large bowl, toss the sweet potatoes with the oil, 1 tsp. salt, and a few grinds of black pepper. Spread the potatoes in a single layer on a large, rimmed baking sheet. Roast for 10 minutes; then flip the potatoes and continue roasting until tender and browned in spots, about 5 minutes more.

While the potatoes roast, heat the butter in a 12-inch skillet over medium-high heat until melted and beginning to brown, 1 to 2 minutes. Add the apples in a single layer and brown on both sides, 1 to 2 minutes per side.

Add the sage and stir until wilted, about 30 seconds. Off the heat, stir in the lemon juice and maple syrup. With a spatula, scrape the apples and butter into the bowl used for tossing the potatoes.

When the potatoes are done, add them to the apples and gently combine with the spatula. Season to taste with salt and pepper, and serve.