Sift sugar, cornstarch and flour together into a medium bowl. Stir and combine with partially thawed strawberries.
In a separate bowl, combine pie crust mix and cold strawberry nectar. Stir until a soft dough forms. Divide into 2 pieces, form into balls, and flatten into disks.
On a lightly floured surface, roll 1 of the disks out to an 11-inch circle. Fold in half, place in a 9-inch pie plate, and unfold. Press into plate, but do not stretch. Trim dough 1/2-inch from edge of plate. Roll out second disk and fold in half. Pour filling into pastry-lined plate. Place top crust on top of filling and unfold. Press along rim to seal and trim edges. Press fork into edges or crimp to make decorative edge. Cut vent slits or punch center with small decorative cutter or knife.
In a small bowl, lightly beat egg, with 1 tablespoon water and 1 tablespoon strawberry nectar. Brush atop crust and then sprinkle with sugar. Place pie on sheet pan* and place in oven.
Bake for 10 minutes, then lower heat to 350 degrees F and continue baking for an additional 50 to 60 minutes; the filling should be bubbling and top crust golden brown. Cool completely before cutting.
*TIP: preheat sheet pan in oven for crisper bottom crust.