SERVES 4
Pommes Anna, “Anna’s potatoes,” is a French gratin dish dating back to the time of Napoleon III. These potatoes are very thinly sliced and arranged in circular layers in a heavily buttered skillet, with additional butter drizzled between the layers. Here we swap in some luxurious truffle oil, and to put your pommes over the top, you’re invited to shave a bit of fresh truffle into the dish.
Tender filet of beef also gets served au gratin, baked in a sauce of egg yolk–enriched cream and Parmesan that includes a medley of mushrooms. Salsify, a winter root that looks like a stick and is related to parsnip, has a flavor reminiscent of oysters, a taste that plays off the earthiness of the mushrooms. To lighten up or simplify this dish, skip the salsify and swap in a mixed green salad.
2½ pounds new potatoes, peeled and sliced very thin, preferably on a mandoline
2 tablespoons unsalted butter, melted
Kosher salt and white pepper
1¼ teaspoons truffle oil
Shaved truffle, optional
Juice of 1 lemon
4 salsify, about 8 inches (2 ounces) each
2 tablespoons olive oil
1 tablespoon unsalted butter
1 pound frozen white pearl onions, defrosted, drained, and patted dry
Kosher salt and freshly ground black pepper
½ cup beef or chicken stock, store-bought or homemade
1 bay leaf
1 sprig thyme
2 sprigs flat-leaf parsley, plus more for garnish
¼ cup olive oil, divided
1 shallot, finely chopped
1 garlic clove, crushed
3½ ounces mixed mushrooms (shiitake, oyster), roughly chopped
3½ ounces crimini mushrooms, roughly chopped
¼ cup heavy cream
1 large egg yolk, lightly beaten
2 tablespoons fresh minced chives
3 tablespoons freshly grated Parmesan cheese, divided
Kosher salt and freshly ground black pepper
4 filet steaks, about 6½ ounces each and 1½ inches thick
PREHEAT the oven to 425°F with the rack in the middle of the oven.
POUR the melted butter into a 10-inch cast-iron skillet, swirling it around so it covers the bottom and comes about a quarter inch up the sides of the pan. Beginning in the center, arrange the potatoes in a circular pattern in the pan, overlapping. Sprinkle with salt and pepper and drizzle with ¼ teaspoon truffle oil and shaved truffle (if using). Repeat layers 3–4 times, ending with truffle oil. Press the potatoes firmly to pack. Cook over medium-high heat for 3 minutes without stirring.
COVER the pan with foil and bake in the oven 30 minutes. Then uncover and bake 20–25 minutes more, until the potatoes are golden brown and tender when pierced with a sharp paring knife. Loosen the edges of potatoes with a spatula or knife. Place a plate upside down on top of pan; invert potatoes onto plate.
WHILE the potatoes are in the oven, braise the onions and salsify.
PREPARE a bowl of cold water and lemon juice, also called acidulated water. Trim both ends of the salsify root. Peel the salsify with a vegetable peeler and cut in to 2-inch pieces. Drop the salsify into the bowl of acidulated water so it doesn’t turn brown.
REMOVE salsify from the water and pat dry. Heat 1 tablespoon of olive oil in a large sauté pan over medium heat. Add the salsify and cook, stirring occasionally, until it begins to turn golden, 4–5 minutes. Season to taste with salt and pepper. Remove from the pan and set aside.
WIPE out the pan, return it to the stove over medium-high heat, and add the remaining tablespoon of olive oil and the butter. Add the pearl onions and sauté until the onions begin to brown evenly on all sides, 8–10 minutes. Add the salsify, stock, bay leaf, thyme, and parsley, cover the pan, and cook 25 minutes until the onions are tender and most of the stock has evaporated. Remove the thyme and parsley, season to taste with salt and pepper, and keep warm.
INCREASE the oven to 450°F and move the rack to the center of the oven.
IN a large sauté pan, heat 2 tablespoons of olive oil over moderate heat. Add the shallot and garlic and sauté until translucent and tender, about 3 minutes. Add the mushrooms, stir so they are well coated, increase the heat to medium-high, and leave in a single layer, undisturbed, for 5 minutes until the mushrooms are browned. Stir and continue cooking for another 2–3 minutes until the mushrooms are browned all over and there is no liquid in the pan. Remove the garlic clove and transfer the mushrooms to a bowl to cool.
USING a whisk, whip the cream until soft peaks form.
FOLD in the mushrooms along with the egg yolk, chives, and a tablespoon of the grated Parmesan, then season with salt and pepper. Set aside.
SEASON the steaks with salt and pepper.
HEAT a large cast-iron or nonstick frying pan until hot—but not smoking—and add the steaks. Cook about 3–4 minutes total time, turning them to brown all over. Remove from the pan.
PUT the steaks in a shallow baking tray. Pile the mushroom mixture on top of the steaks and dust with the remaining Parmesan. Cook in the oven, uncovered, for 7–9 minutes until the steak is rare (internal temperature 120°F) and the topping is golden.
DIVIDE the steaks among 4 plates. Serve with a slice of Pommes Anna and the braised vegetables. Garnish with a sprig of parsley.