Make the pastry crust: In a food processor, pulse the chilled butter and flour until the mixture resembles coarse crumbs. Add ice water, 1 tablespoon at a time, and pulse until the dough just begins to hold together. Form the dough into a disc, wrap in plastic, and refrigerate for at least 30 minutes.

Preheat the oven to 375°F (190°C).

Roll out the chilled dough and cut into circles to fit individual tart pans. Press the dough into the pans, trimming any excess.

In a bowl, toss the sliced strawberries with sugar and cornstarch until evenly coated.

Divide the strawberry mixture evenly among the prepared tart shells.

Bake the tartlets for 18-20 minutes, or until the crust is golden brown and the filling is bubbling.

Allow the tartlets to cool completely before serving.