Beef Wellington

Pat the 800g trimmed beef tenderloin completely dry with paper towels, then rub evenly with 1 teaspoon (6g) kosher salt and ½ teaspoon (1g) black pepper. Heat 1 tablespoon (15ml) olive oil in a heavy-bottomed skillet over high heat until shimmering. Sear the beef on all 4 sides for 1.5 minutes per side, until a deep golden-brown crust forms (total searing time 6 minutes). Transfer beef to a plate, brush all over with 2 tablespoons (30ml) Dijon mustard while warm, then set aside to cool completely to room temperature (about 20 minutes).

In the same skillet used for searing, melt 2 tablespoons (30g) unsalted butter over medium heat. Add 100g minced shallots and cook for 3 minutes until soft and translucent, then add 15g minced garlic and cook 30 seconds until fragrant (do not let garlic burn). Add 450g finely chopped cremini mushrooms, 1 tablespoon (3g) fresh thyme leaves, remaining ½ teaspoon (3g) kosher salt, and ½ teaspoon (1g) black pepper. Cook, stirring occasionally, for 12-15 minutes until all mushroom liquid fully evaporates and the mixture forms a thick, dark, spreadable paste with no remaining moisture. Transfer duxelles to a plate to cool completely to room temperature (about 20 minutes).

Lay a 30cm long sheet of plastic wrap flat on your clean work surface. Arrange the 12 slices of prosciutto in slightly overlapping horizontal rows on the plastic to form a 20cm x 28cm rectangle large enough to fully enclose the beef, leaving no gaps between slices. Spread the cooled duxelles evenly over the prosciutto in a thin, uniform layer, leaving a 1cm border around all edges. Place the cooled, mustard-coated beef tenderloin horizontally across the exact center of the prosciutto-duxelles layer.

Use the edges of the plastic wrap to tightly lift the prosciutto and duxelles up and over the beef, rolling firmly to create a tight, even log, pressing out any trapped air pockets as you work. Twist the open ends of the plastic wrap tightly to seal completely, then roll the log back and forth a few times on the counter to create a smooth, uniform cylinder shape. Transfer the wrapped log to the refrigerator to chill for 20 minutes, until it holds a firm, solid shape for easy pastry wrapping.

Lightly dust your clean work surface with 1 tablespoon (10g) all-purpose flour, then roll the 500g all-butter puff pastry out to a 3mm thick rectangle measuring roughly 35cm x 25cm, large enough to fully enclose the beef log. Remove the plastic wrap from the chilled beef log and place it horizontally in the center of the rolled pastry. Brush all exposed pastry edges with half of the beaten egg wash. Fold the pastry tightly over the beef, pressing edges firmly to create a tight seal, and trim any excess thick pastry to avoid doughy seams. Place the wrapped Wellington seam-side down on a parchment-paper-lined baking sheet, then brush the entire outer pastry surface with the remaining beaten egg wash. Cut 3 small 2cm slits in the top of the pastry to allow steam to escape during baking, then chill for another 15 minutes while the oven preheats.

Preheat your oven to 200°C (400°F) with a rack positioned in the middle. Once the oven is fully preheated, place the chilled Wellington on the middle rack and bake for 35-40 minutes, until the pastry is a deep, even golden brown and crisp all over, and the internal temperature of the beef reaches 55°C (131°F) for perfect medium-rare doneness (check by inserting an instant-read thermometer through one of the top steam slits). Remove the Wellington from the oven and transfer it to a wooden cutting board to rest for 15 minutes before slicing into 2.5cm thick pieces to serve.