For beef Wellington packed with flavor, we salted beef tenderloin overnight and then slathered it with piquant Dijon mustard before wrapping it in umami-rich prosciutto spread with superconcentrated duxelles. We traded the traditional puff pastry for sturdier, easier-to-work-with pâte brisée, which produces a firm yet flaky and tender crust that slices neatly when serving. Finally, we tackled the biggest challenge of making a Wellington: producing both a perfectly baked crust and uniformly medium-rare beef. To accomplish this, we roasted the Wellington in a 450-degree oven and removed it when the beef registered a mere 85 degrees. Carryover cooking did the rest of the work, as the meat's temperature gradually rose to 130 degrees (medium-rare). We created a Creamy Green Peppercorn Sauce and a Madeira Sauce, which gave us two options for finishing the decadent dish.