I first discovered hanger steak, known in France as onglet, during my student days in Paris. I loved its juicy, fibrous texture and its rich, meaty, almost sanguine flavor: I loved its price; as it was one of the few steaks I could afford on a student budget. Hanger steak was a bistro and neighborhood cafe favorite and always came with some variation on a shallot sauce. The trick was to thinly slice the steak across the grain to shorten the meat fibers and make the meat tender. While hanger steak is no longer the bargain it used to be, it rewards you with a fabulous flavor for a fraction of the price of one of the more prestigious steaks.
Step 1: Place the cornstarch and 1 tablespoon of the wine in a small bowl and stir to blend. Set the mixture aside.
Step 2: Melt 1 tablespoon of the butter in a heavy saucepan over medium heat. Add the bacon and cook 2 minutes to render some of the fat. Add the shallots, garlic, and mushroom, if using, and cook until the ingredients begin to brown, about 5 minutes. Add the remaining wine, the stock, and 1 tablespoon of the parsley to the saucepan, Increase the heat to high, and boil the mixture until it’s reduced to about 1 1/2 cups, about 15 minutes.
Step 3: Stir the cornstarch mixture to reblend it, then whisk it into the boiling sauce to slightly thicken the sauce. (If this book was about classic French cuisine, you’d strain the sauce. I prefer it with the bits of bacon, shallots, and mushroom, so I don’t bother.) Whisk in the remaining 2 tablespoons butter and 2 tablespoons of the parsley and season with salt and pepper. The sauce should be highly seasoned. Keep warm or on a corner of the grill (see Tip, below.)
Step 4: Set up the grill for indirect grilling and preheat it to high.
Step 5: When ready to cook, brush and oil the grill grate. Place the steak on the hot grate and grill until cooked to taste; it tastes best served rare or medium-rare, about 2 minutes per side fro rare; 3 minutes per side for medium-rare.
Step 6: Transfer the grilled steak to a platter or plates. Slice the steak sharply on the diagonal. Spoon the sauce over the steak and sprinkle the remaining 1 tablespoon of parsley on top.
If you are preparing the sauce more than 15 minutes ahead, do not add the final butter and parsley. Instead, bring the sauce to a boil right before serving and whisk them in at the last minute.