Flank Steak with Mushroom Sauce
Serves 4 to 6
1 flank steak, trimmed, about 1-1/2 to 2 pounds
1 750 ml bottle dry red wine
1 small onion, coarsely chopped
2 garlic cloves, smashed and peeled
1 branch fresh rosemary, or 1 teaspoon dried
6 stems fresh thyme, or 1/2 teaspoon, dried
1 teaspoon soy sauce
1 teaspoon Worcestershire sauce
Salt and freshly-ground black pepper
1/2 ounce dried porcini mushrooms (about 1/2 cup)
8 ounces sliced fresh mushrooms
1 tablespoon vegetable oil
2 tablespoons unsalted butter
Marinate the steak at least a few hours or overnight if possible. Combine the red wine, onion, garlic, rosemary, thyme, soy, Worcestershire, and a little salt and pepper in a gallon-size zipper bag (or a 13 x 9 -inch nonreactive pan). Put the steak in and turn it to coat. Zip close or cover, and refrigerate for at least 4 hours. (If you’re in a hurry, leave it at room temperature for an hour).
Take the steak out of the marinade and pat it dry. Sprinkle both sides with salt and pepper and set it aside while you make the sauce. This is the time to heat up your grill, the grill pan, or the broiler.
Pour the marinade into a medium saucepan. Rinse the dried mushrooms in cold water to remove any grit, then add them to the marinade. Bring it to a boil over high heat, and skim off any scum that rises to the surface. Lower the heat but keep it boiling, you’ll want to reduce it by a little more than half to 1-1/4 cups, about 20 minutes.
While the sauce is boiling away, cook the steak — about 4 minutes each side for rare, 5 for medium-rare. Transfer the meat to a plate and loosely cover it with foil. Let it sit for at least 20 minutes to cool off and redistribute the juices.
Then cook the mushrooms. Heat the vegetable oil in a large nonstick skillet over medium-high heat until you see it shimmer. Add the mushrooms and a little salt and pepper. Shake the pan to distribute the mushrooms over the bottom. Crank the heat to high and leave the mushrooms alone for a minute. Using a spatula, turn them over quickly and cook on high for another minute. Transfer them to a plate to cool off.When you’re ready to serve, strain the sauce and return it to the pan along with the mushrooms, along with any juice that came out of the mushrooms and the steak. Bring the sauce to a simmer, and add the butter, whisking it in to mix. Taste for salt and pepper. Slice the steak very thinly across the grain and serve with the sauce on top.