Preheat the oven to 350°F (175°C). Line the baking pan with parchment paper for easy removal.
Combine 1 1/2 cups of flour, 1/2 cup of sugar, and cold cubed butter in a mixing bowl. Use a pastry cutter or your fingertips to cut the butter into the dry ingredients until the mixture resembles coarse crumbs with pea-sized bits.
1 1/2 cups all-purpose flour
Press two-thirds of the crumb mixture evenly into the bottom of the prepared baking pan to form the crust. Bake for 15 minutes until lightly golden.
1 1/2 cups all-purpose flour
In a mixing bowl, combine sliced strawberries, lemon zest, lemon juice, 2 tablespoons of sugar, and cornstarch. Mix until well coated and thickened slightly.
1 1/2 cups all-purpose flour
Pour the strawberry lemon filling evenly over the baked crust. Spread with a spatula to create an even layer.
1 1/2 cups all-purpose flour
Sprinkle the remaining crumb mixture evenly over the filling. Bake for an additional 30 minutes, until the topping is golden brown and the filling is bubbling around the edges.
1 1/2 cups all-purpose flour
Allow the bars to cool completely in the pan on a wire rack. Once cooled, cut into squares and serve.