This is my take on a recipe I saw on the Food Network. It turned out SO good. My husband doesn't even like mushrooms, and he loved this. It's a little more time-consuming, but worth it!
* 1 sirloin steak (about 2-inches thick)
* Salt and freshly ground black pepper
* 2 sheets puff pastry, thawed
* 1/2 cup dijon mustard
* 1 egg
* 1 tablespoon olive oil
* Sauteed Wild Mushroom Sauce, recipe follows
Preheat oven to 350 degrees F, and preheat grill to medium-high.
Season beef with salt and pepper and set aside.
Unfold puff pastry and evenly brush 1 sheet with mustard, covering entire surface. Unfold second puff pastry and place on top of the first, then cut into 4 equal pieces. Press the pastry edges with tines of a fork to seal and cut 3 small slits halfway deep in the center of each pastry rectangle to allow steam to escape when it cooks. Set pastry rectangles on a baking sheet lined with parchment. In a small bowl whisk egg with 1 teaspoon water. Brush pastry rectangles with egg wash and bake 25 minutes, until golden and cooked through.
Brush beef with oil. Season with salt and pepper and grill until it's medium-rare. Remove beef from the grill and place on a cutting board. Let meat rest 10 minutes before slicing. To serve, place a puff pastry rectangle on each serving plate. Top with beef slices and drizzle with Sauteed Mushroom Sauce.
Sauteed Wild Mushroom Sauce:
* 2 tablespoons butter
* 2 tablespoons olive oil
* 1 clove garlic, minced
* 1 sprig fresh thyme, leaves chopped (or about 1/4 t. dried)
* 1 1/2 pounds mushrooms, wiped clean and sliced
* Kosher salt and freshly ground black pepper
* 1/2 cup heavy cream
* 4 teaspoons dijon mustard
Heat a saute pan to medium heat. Add butter and olive oil. Add garlic and thyme leaves and saute for 3 minutes. Add mushrooms, salt and pepper, saute until golden and tender, about 10 minutes. Cook in batches, if necessary, so that the mushrooms don't steam. Return all mushrooms to pan, if working in batches. Add heavy cream and mustard and simmer 5 minutes, stirring occasionally. Serve immediately.