The combination of tender salmon, fresh cucumber sauce and a crisp, flaky crust makes this impressive dish perfect for special occasions. Mom likes to decorate the pastry with a star or leaf design for holidays.
Preheat oven to 400°. On a lightly floured surface, roll each pastry sheet into a 12x10-in. rectangle. Cut each into two 10x6-in. rectangles. Place a salmon fillet in the center of each rectangle.
Beat egg and water; lightly brush over pastry edges. Bring opposite corners of pastry over each fillet; pinch seams to seal tightly. Place seam side down in a greased 15x10x1-in. baking pan; brush with remaining egg mixture.
Bake until pastry is golden brown, 25-30 minutes. In a small bowl, combine the cucumber, sour cream, mayonnaise, dill and salt. Serve with bundles.