In a medium saucepan, combine fresh strawberries, lemon juice, and sugar over medium-low heat. Cook for about 10 minutes until softened.

Mix cornstarch with cold water, then add it to the strawberries, cooking until thickened for 2-3 minutes. Remove from heat and cool slightly.

On a clean surface, sprinkle half of the additional sugar and roll out puff pastry to about 1/8 inch thick. Coat both sides with remaining sugar.

Spread a thin layer of cooled strawberry mixture over the pastry, roll both sides towards the center, wrap in plastic wrap and freeze for 30 minutes.

Preheat oven to 350°F (180°C) and line a baking sheet with parchment paper. Slice the frozen log into 1/2 inch pieces.

Arrange the slices on the baking sheet and bake for 25-30 minutes until golden brown. Allow cooling before serving.