Foryoueats: The Ultimate Beef Wellington Recipe

Ingredients

• 1 center-cut beef tenderloin, trimmed of silverskin and fat, about 2 pounds (see note)
• Kosher salt and freshly ground black pepper
• 2 tablespoons plus 1/2 teaspoon vegetable or canola oil, divided
• 2 tablespoons prepared horseradish
• 1 tablespoon Dijon, spicy brown, or hot English mustard
• 1 pound mushrooms (button, cremini, shiitake, portabello, or a mix) cleaned, trimmed, and roughly chopped
• 4 tablespoons unsalted butter
• 2 medium shallots, finely diced (about 1/2 cup)
• 2 teaspoons finely minced fresh thyme leaves
• 1/2 cup Cognac or other brandy or barrel-aged spirit, such as bourbon
• 1/2 cup heavy cream
• 2 teaspoons soy sauce
• 4 ounces fresh foie gras (about two 1/2-inch slabs, see note)
• 1 sheet phyllo dough
• 1/4 pound prosciutto, sliced paper thin
• Flour, for dusting
• 14 ounces frozen or homemade puff pastry, thawed (see note)
• 1 egg, beaten
• Coarse sea salt, such as Maldon or fleur de sel
• 1 bunch finely minced chives