Buffet Salmon en Croute
1/4 cup unsalted butter
1 1/2 pounds fresh mushrooms, coarsely chopped
3 large shallots, chopped
Salt and freshly ground black or white pepper
Spinach and Garlic
1 tablespoon olive oil
2 cloves garlic, minced
2 (10-ounce) packages frozen spinach, thawed and squeezed dry
1(1-or 11/4-pound) package puff pastry, thawed in the refrigerator overnight
1(2-to 21/2-pound) tail-end-salmon fillet, skinned
1 large egg
2 teaspoons water
Salt and freshly ground black or white pepper
1 bunch fresh dill, chopped (optional)
To prepare the mushrooms, melt the butter over medium-high heat in a large skillet. Add the mushrooms and shallots and saute until well cooked and all the liquid has evaporated, about 10 minutes. Season to taste with salt and pepper. Transfer to acovered container and refrigerate until completely cold, up to 1 day in advance.
To prepare the spinach and garlic, heat the olive oil over medium heat in a skillet. Add the agrlic and saute until soft but not browned, about 11/2 minutes. Add the spinach and stir until hot. Season to taste with salt. Transfer to a covered container and refrigerate until completely cold, up to 1 day in advance.
Lightly flour a clean work surface and set out the chilled puff pastry. Let the pastry sit just long enough to become pliable, so it won't break or crack when you unfold it; puff pastry is easiest to work with chilled because it will stretch and tear at room temperature. Be prepared to chill the pastry anytime it becomes warm by clearing part of a shelf in the refrigerator for the baking sheet.
Line 1 or 2 large baking sheets with parchment paper (important because it will absorb the excess butter from the pastry while baking). With a sharp knife, carefully cut the salmon fillet in half lengthwise into 2 equal portions. Drain off any accumulated liquid from the mushroom and the spinach mixtures and then set them to the side of your workspace. In a small bowl, combine the egg and water for the egg wash and beat with a fork until foamy.
Unfold 1 of the sheets of the chilled puff pastry with the longer edge facing you; do not roll out. Mentally make a note of the middle of the pastry; you will be working with the bottom half (the top half will be folded over the salmon). Working quickly and being attentive to the temperature of the pastry, spread half of the spinach mixture over the bottom half of the pastry, leaving a 1-inch border on all sides. Spread half of the mushroom mixture over the top of the spinach and then lay 1 of the salmon fillets on top. Season with salt and pepper and sprinkle with some of the dill.
With a pastry brush or your fingers, moisten the edges of the pastry all the way around with the egg wash, being careful not to let the egg drip down the side (the egg wash will glue the layers together and interfere with the rising). Fold the top half of the pastry over the salmon, so that the top edges line up perfectly with the bottom edges. Press the edges firmly together on all three sides and then crimp witht he tines of a fork. (To avoid warming the pastry, don't handle the dough with your fingers more than is necessary.) Transfer the pastry with a metal spatula to the lined baking sheet. Repeat with the remaining ingredients. Place both pastries on 1 baking sheet if they can fit without touching each other; otherwise place on seperate baking sheets.
With the tip of a knife, create a steam hole in the top of each pastry and in a few places along the edge. For a shiny, golden surface, brush the tops with the egg wash, being careful not to let the egg drip down the edges of the pastry, and cover loosely with plastic wrap. Place in the refrigerator and chill for at least 1 hour and up to overnight before baking.
To bake, preheat the oven to 450ºF. (The oven needs to be very hot before you put the pastry in, to ensure it rises properly.) Remove the plastic wrap, place the baking sheet on the center rack of the oven, and bake for 15 minutes. Decrease the temperature to 350ºF and bake an additional 15 to 20 minutes, until the pastry is golden brown and puffed. Remove from the oven and let rest for at least 30 minutes before cutting. Cover with foil to transport.
The salmon can be served plain or with a simple yet delightfully delicious sauce of just pureed red peppers and cream. To prepare the sauce, drain a 16-ounce jar of roasted red peppers and puree until smooth in a food processor. Transfer to a small bowl and whisk in 1/2 pint heavy cream. Taste for seasoning. The sauce can be made the day ahead and refrigerated, covered. When ready to serve, heat until steaming in the microwave or in a small saucepan on the stovetop, then transfer to a serving bowl with a small ladle for drizzling over the slices of salmon. Makes about 21/2 cups.