To make the mushroom stuffing, in a large, heavy skillet melt the butter over medium-high heat. Add the shallots and garlic, and cook, stirring, for 1 minute. Add the mushrooms, salt, and pepper, and cook, stirring, until the mushrooms are wilted and begin to caramelize, 10 to 15 minutes. Add the wine and cook, stirring to deglaze the pan and until the liquid has almost all evaporated and the mixture is tight, about 5 minutes. Stir in the parsley and remove from the heat. Let cool completely before using.
Season the pork tenderloins with the Essence.
Heat the oil in a skillet or Dutch oven large enough to hold the tenderloins over medium-high heat. Add the tenderloins and reduce the heat to medium. Sear evenly on all sides and cook, turning frequently. Remove pork from the pan and cool for 10 minutes.
Preheat the oven to 400 degrees F.
Line a large baking sheet with aluminum foil and lightly grease. Set aside.
On a lightly floured surface, roll out the pastry to a 12 by 18-inch rectangle. Place the pork tenderloins on 1/2 of the puff pastry, leaving a 1-inch border around the edges. Evenly coat the tenderloins on all sides with the mustard.
Pack the cooled mushroom mixture around the pork tenderloins. Brush a 1/2-inch border of egg wash on the pastry around the meat. Gently pull the remaining pastry over the meat to completely enclose, and press gently to seal. With a small knife cut away the excess pastry to make an even border and crimp the pastry edges with a fork dipped in flour. Make a small slit in the top of the pastry for steam to vent.
Carefully transfer the tenderloin to the prepared baking sheet. Brush the pastry evenly with egg wash. Bake for 10 minutes, then rotate the pan. Bake until golden brown and an instant read thermometer reaches 140 degrees F, an additional 8 to 10 minutes. Remove from the oven and let rest for 5 minute before serving.
Slice the pork tenderloin and serve with the Haricots Verts.
Essence (Emeril's Creole Seasoning):
Yield:about 2/3 cup
Combine all ingredients thoroughly and store in an airtight jar or container.
Recipe from "New New Orleans Cooking", by Emeril Lagasse and Jessie Tirsch. Published by William and Morrow, 1993.
In a saute pan, melt the butter. Add the garlic and shallots and saute until the shallots begin to soften. Add the haricot vert, lemon juice and zest and cook until crisp-tender – about 3 minutes. Add the marjoram and season, to taste, with salt and pepper.