Blue Cheese Stuffed Tenderloin
1 (7 ounce) center-cut beef tenderloin filet, trimmed 4 ounces good-quality blue cheese, crumbled
1/4 pound pancetta, thinly sliced
Kosher salt and freshly ground black pepper
2 cups heavy cream
Sachet (1 teaspoon whole black peppercorns, 1 dried red chile, 4 fresh thyme sprigs, and 2 bay leaves put in cheesecloth and tied with kitchen string)
1/2 pound baby leeks, well-washed, roots trimmed, and sliced
2 tablespoons extra-virgin olive oil
1 shallot, thinly sliced
1/2 cup red wine, such as Cabernet Sauvignon
1/4 cup Demi-glace (Homemade or Store Bought)
2 tablespoons unsalted butter
2 fingerling potatoes, thinly sliced lengthwise on a mandoline
Canola oil, for frying
White truffle oil, for drizzling
Chervil sprigs, for garnish
Using a sharp knife, make a horizontal incision across the center of the beef, without cutting all the way through. Stuff the blue cheese into the pocket and squeeze the sides of the meat together to close. Take the slices of pancetta so you have long, thin strips. Coil the pancetta around the circumference of the tenderloin to cover; season all over with salt and pepper. Set aside.
To prepare the leeks: Combine the cream and sachet in a medium saucepan and bring to a simmer over low heat.
Bring a medium pot of lightly salted water to a boil. Boil the leeks for 30 seconds; Scoop the leeks out of the water and add them to the cream. Cook the leeks in the cream for 10 minutes until thick and creamy.
Preheat the oven to 375°F.
Place a large sauté pan over medium heat and coat with the olive oil. Lay the beef in the pan and sear for 5 minutes without moving it around, until the meat has a caramel brown crust. Turn the meat over with tongs and cook the other side for 2 minutes. Transfer the beef to a baking pan. Finish cooking in the oven for 8 to 10 minutes or until the internal temperature of the meat reaches 130°F. Put the sauté pan back on the heat to make the sauce.
Add the shallot to the meat drippings; cook and stir for 2 minutes until they soften. Deglaze with the wine, stirring to evaporate and until almost dry. Mix in the Demi-glace, stirring to liquefy; add a couple of tablespoons of water to thin it out if needed. Add the butter, stirring to melt. Strain the sauce. Taste and adjust the seasoning if necessary.
To prepare the potato chip garnish: Heat 2-inches of canola oil in a wide pot. When the oil is hot, fry the potato slice until crisp and golden. Remove to a side plate lined with paper towels to drain. Drizzle the chips with a little truffle oil.
To serve: Place a mound of the creamy leeks in the center of the plate. Rest the beef on top of the leeks and drizzle the red wine sauce around the plate. Set a couple of the potato chips on top. Garnish with chervil sprigs.