Preheat the oven to 400 F and prepare two baking sheets by lining with parchment paper.
Collect about 1 tsp zest from the lemon and juice it. In a separate bowl, whisk the egg with 1 tbs water. Set aside.
In a mixing bowl, combine cream cheese, lemon zest, and sugar if using. Beat until creamy.
Unfold the pastry sheet onto a lightly floured surface, then lightly roll to flatten. Cut in thirds along the folds, then cut each strip in half. Each sheet will yield 6 rectangles.
Transfer the rectangles to the baking sheets and place them about 2 inches apart from each other. Using a small, sharp knife, score a border about 1/4 inch from the edges. That'll help the dough rise evenly while it's baking.
Next, divide the cream cheese between the rectangles, trying to stay within the border. Top with fruit, then sprinkle about 1/8 to 1/4 tsp lemon juice directly onto the fruit. Brush the edges with the egg wash.
Bake until golden and puffed, about 15 to 18 minutes. Remove from oven and let cool on baking sheet for 5 minutes before transferring to a baking sheet to cool completely.