Start with the filling: in a large saucepan, whisk the sugar and cornstarch together. Gradually pour in the boiling water, then place the pan over medium-high heat. Stir continuously until the mixture transitions from clear to a milky gel, which should take about 7 minutes as it comes to a boil. Once it reaches that gel consistency, take the pan off the heat.
Stir in the strawberry jello and the prepared strawberries, then set the filling aside to cool slightly. Meanwhile, for the crust, combine the flour, salt, and sugar in a 9-inch pie plate. Make a well in the center and pour in the vegetable oil and milk. Mix gently until a dough forms, then press it evenly into the pie plate. Pinch the edges to create a fluted design. Finally, poke at least 5 fork holes into the bottom of the crust with a dinner fork; this helps steam escape and keeps the crust from buckling.