Preheat oven to 400°F. Line two baking sheets with parchment paper and set aside.
On a lightly floured surface, lay out the thawed puff pastry sheets. Cut each sheet into 6 equal rectangles (about 4 ½ × 3 inches), for a total of 12 pastries.
Arrange the rectangles on the prepared baking sheets, leaving about 1 inch between each pastry.
Using a fork, gently poke holes in the center of each rectangle, avoiding the edges. This helps the outer border puff while keeping the center flat for the filling.
In a small bowl, combine cream cheese, granulated sugar, vanilla extract, and salt until smooth. Stir in lemon zest if using. Set aside.
In another small bowl, toss strawberries with sugar and cornstarch. Let sit for 5 minutes, then gently drain off excess liquid.
Spread about 1 tablespoon of the cream cheese mixture onto the center of each pastry.
Top with the prepared strawberries, layering evenly over the cream cheese.
In a small bowl, whisk the egg with water. Brush the edges of each pastry rectangle with the egg wash to achieve a golden, glossy finish.
Bake for 15 to 18 minutes, or until the pastries are puffed and golden brown.
Remove from oven and let cool slightly.
(Optional) Dust with confectioners’ sugar before serving. For a glossy, bakery-style finish, lightly warm strawberry jam or jelly and brush it over the strawberries after baking; it adds shine and a touch of extra sweetness.