Wrap the beef tightly in a triple layer of plastic wrap, shaping it into a neat cylinder. Let it chill in the refrigerator overnight to set its shape (or at least 30 minutes).
Make the Mushroom Duxelles
Start by finely dicing baby bella mushrooms. While some recipes suggest using a food processor, dicing the mushrooms by hand gives the duxelles a more textured, satisfying bite.
Heat a couple of tablespoons of oil in a pan over medium heat before adding the diced mushrooms. The oil will help the mushrooms cook evenly and prevent them from sticking. Season with salt, pepper, and fresh thyme.
As the mushrooms cook, they will release a significant amount of liquid. Continue cooking them until all the moisture is released and fully evaporated.
Set them aside and allow the duxelles to cool fully before layering them.
Make the Chive Crepes
In a large mixing bowl, whisk together eggs, flour, milk, chives, thyme, and salt until smooth. Chill the batter in the fridge for at least 30 minutes.
Heat a nonstick pan over low heat and lightly spray it with cooking oil. Add ¼ cup of the crepe batter, swirling the pan to spread it into a thin, even layer. Cook for about 25-30 seconds until the crepe is set, then carefully flip it and cook for just a few more seconds. The crepes should stay pale without browning. Remove and set aside. Repeat.
Sear and Season the Beef
After chilling the beef tenderloin in the fridge, remove the plastic wrap and pat the beef dry with paper towels to remove any excess moisture. This helps the meat sear properly. Season the beef generously with salt and pepper on all sides.
Heat a cast iron skillet over high heat until it’s smoking hot. Add a little oil with a high smoke point (such as avocado or grapeseed oil). Place the beef in the pan and sear each side for 60 seconds, including the ends.
Once seared, transfer the beef to a tray and pour any juices from the pan over it. While the beef is still hot, brush it all over with Dijon mustard. Set aside to rest.
Assemble the Wellington
Moisten a cutting board with a damp towel, then layer three pieces of plastic wrap, overlapping them. Trim 2 crepes into squares that match the length of your beef, and lay them out on the plastic wrap.
Next, evenly lay slices of prosciutto over the crepe. Ensure the slices overlap slightly to create a solid layer to hold the beef and mushrooms in place.
Evenly spread the cooled mushroom duxelles over the prosciutto.
Using the plastic wrap, roll the beef tightly in the crepes, prosciutto, and mushrooms to form a neat package. Twist the ends of the plastic wrap to secure it, and chill in the fridge for 20 minutes.
Wrap in Puff Pastry
Moisten the cutting board again and lay out three pieces of plastic wrap. Using a rolling pin, roll the puff pastry into an ⅛-inch-thick rectangle.
Once the pastry is rolled out, carefully place the wrapped crepe roll in the center. Position it lengthwise, allowing enough pastry on either side for wrapping.
Brush the edges of the pastry all around with an egg wash (a mixture of beaten egg and a splash of water).
Using the plastic wrap, carefully roll the puff pastry around the crepe and beef, forming a tight cylinder. Ensure that the seam is on the bottom to maintain an elegant presentation. After rolling, let the wrapped Wellington chill in the refrigerator for about 30 minutes.
Once chilled, take the Wellington out of the refrigerator and carefully unwrap it from the plastic wrap. Brush the entire exterior of the puff pastry with the egg wash. This step is essential for achieving a beautiful, golden-brown color as it bakes.
Baking, Resting, and Slicing
Preheat your oven to 425°F for convection or 450°F for a regular oven.
Transfer the Wellington to a baking tray lined with parchment paper. This prevents sticking and allows for even cooking.
Place the tray in a preheated oven at 425°F (220°C). Bake until the internal temperature reaches 135°F (57°C) for medium-rare. This can take anywhere from 20 to 40 minutes, depending on your oven and the starting internal temperature of the beef.
Remove the Wellington from the oven and allow it to rest for at least 15 to 20 minutes. If desired, you can lightly cover the Wellington with aluminum foil during the resting period to keep it warm. Be careful not to wrap it too tightly, as this can trap steam and soften the pastry.
After resting, use a sharp, serrated knife to slice the Wellington into even portions. Aim for about 1-inch thick slices to showcase the beautiful layers of beef, mushrooms, prosciutto, and pastry.
Video
Notes
Refer to the blog post for detailed tips, notes, and a picture tutorial. There's just too much information to put here.