Beef Wellington

Season the tenderloin all over with the 2 teaspoons salt and the pepper, then tie it with kitchen twine at 1-inch intervals into an even cylinder. Even thickness end to end is what gives you an even pink center later. Refrigerate uncovered on a rack for at least 4 hours, or overnight if you have it.

Make the duxelles. Working in batches, pulse the mushrooms in a food processor until they look like coarse couscous — 10 to 12 short pulses. Do not let them turn to paste. Pulse the shallots and garlic separately until finely minced.

Melt the 3 tablespoons butter with the olive oil in a wide skillet over medium-high heat. Add the mushrooms and cook, stirring often, for 20 to 25 minutes. They'll release a startling amount of water, then go quiet, then start to squeak and pull away from the pan.

That last stage is the whole recipe. Wet duxelles is why Wellingtons come out soggy, and there is no fixing it later. Cook until the pan is dry and the mixture holds its shape when you push it.

Add the shallots, garlic, thyme, and 1 teaspoon salt and cook 3 to 4 minutes more. Deglaze with the sherry and cook until the pan is dry again. Spread the duxelles on a sheet pan and cool completely.

Make the crepes. Whisk the flour, milk, eggs, and pinch of salt until perfectly smooth, then rest the batter 20 minutes. Stir in the chives.

Heat a 10-inch nonstick skillet over medium with a little butter. Pour in a thin ladle of batter, swirl to coat, and cook about 1 minute per side. Make 3 or 4 crepes and cool them flat.

Heat the grapeseed oil in a cast-iron skillet over high heat until smoking. Sear the tenderloin 60 to 90 seconds per side, turning to hit all four sides and both ends — 4 to 5 minutes total. You want deep brown, not gray.

Move the beef to a plate, snip and remove the twine, and brush the entire surface with the Dijon mustard while it's still hot. Cool 20 minutes, then refrigerate until cold to the touch.

Lay a large sheet of plastic wrap on the counter. Shingle the prosciutto slices into a rectangle wide enough to wrap fully around the beef and about 2 inches longer than it at each end.

Lay the crepes over the prosciutto in a single layer, trimming them to the same footprint. The crepe layer is the moisture barrier between the duxelles and the pastry — it is not decorative.

Spread the cooled duxelles over the crepes in an even layer about 1/4 inch thick, leaving a 1-inch border along the far edge.

Set the beef along the near edge. Using the plastic wrap to drive it, roll everything into a tight cylinder, then twist both ends of the plastic like a candy wrapper to compress it. Refrigerate 30 minutes.

Roll the puff pastry on a lightly floured surface to about 1/8 inch (3 mm) thick and roughly 14 by 12 inches. Work fast and keep it cold — warm butter in the pastry means no layers in the oven.

Unwrap the chilled roll onto the pastry. Brush the far edge with egg wash, roll the pastry around the cylinder, and trim any overlap so the seam is a single thickness, not a double one. Press the seam closed, then fold and press the ends shut.

Wrap the whole Wellington tightly in fresh plastic, twist the ends, and chill another 30 minutes. Chilling between every stage is the difference between a clean slice and a collapse.

Preheat the oven to 425°F (220°C) with a rack in the lower-middle position. Line a sheet pan with parchment.

Unwrap the Wellington and set it seam-side down on the pan. Brush all over with egg wash, chill 10 minutes, then brush a second time. Two coats is what gives you the lacquered finish.

Score the top lightly with the back of a paring knife in a diagonal crosshatch, cutting into the pastry but never through it. Sprinkle with flaky salt.

Bake 40 to 45 minutes, until the pastry is deep golden and an instant-read thermometer through the end reads 120°F to 125°F (49°C to 52°C) for medium-rare. Start checking at 30 minutes and tent loosely with foil if the pastry colors too fast.

Rest the Wellington on a rack for a full 15 minutes. Carryover brings the center to about 130°F (54°C) and the juices settle back into the meat. Cut it early and you lose all of it on the board.

Slice 1 to 1 1/2 inches thick with a sharp serrated knife, using long strokes and wiping the blade between cuts. Serve the ends to whoever helped, and take the middle. You built this over twenty-four weeks — eat it like you know that.