Preparation

Preheat oven to 400°F. Sprinkle a baking sheet with water and place the puff pastry on it. Prick the pastry well with a fork. Place a heatproof cup or tin, about 2 inches high, on each corner of the baking sheet; rest a wire rack on top of them (this will prevent the puff pastry from rising unevenly). Bake for 15 minutes. Reduce oven temperature to 350°F and bake until pastry is golden - about 12 minutes more. Cool on a rack. Cut the cooled pastry into 4 equal rectangles.

Melt 1 tablespoon butter in a small non-aluminum saucepan over medium-high heat. Add shallot and cook until soft and yellow but not brown. Add wine and boil until reduced to 2-3 tablespoons liquid. Add cream, salt and cayenne pepper and boil for 4 minutes, stirring constantly. Keep sauce warm.

Melt 1 teaspoon butter in a large skillet over high heat. Add salmon and cook for about 2 seconds on each side.

Split each rectangle of puff pastry open as though cutting a roll for a sandwich. Place the bottom halves on 4 separate plates. Divide about half of the salmon over the pastry; top with the upper half of the pastry and finish with another layer of salmon. Spoon sauce over and around the pastry. Sprinkle with chopped sage and serve.