In a large bowl whisk flour, sugar, and salt.
Cut in cold butter with pastry blender or fingertips until mixture looks like coarse crumbs with pea-sized bits of butter.
Drizzle in ice water 1 Tbsp at a time, tossing with a fork until dough just holds when pinched (don’t over-mix).
Divide in half, shape each into a disc, wrap in plastic or beeswax wrap. Chill at least 1 hour (or up to 2 days).
In a large bowl, gently toss strawberries with sugar, balsamic, basil, salt, cornstarch, grated apple, lemon zest, and juice.
Let stand 10–15 min; it’ll get glossy but not soupy — that’s perfect.
Preheat oven to 400°F / 200°C.
Roll one dough disc to about a 12-inch round on a lightly floured surface. Fit into a 9-inch pie dish; leave about 1-inch overhang.
Spoon strawberry mixture into crust evenly.
Roll second dough disc to a 12-inch round. Cut into ¾- to 1-inch strips.
Arrange strips in a lattice pattern over filling; trim, fold edges under bottom crust, and crimp.
Brush lattice & edges with egg wash, sprinkle with coarse sugar.
Bake at 400°F for 20 minutes.
Reduce heat to 350°F / 175°C and bake 30–35 minutes more, until lattice is golden-brown and thick bubbles appear in center.
If edges brown too fast, tent with foil.
Cool on a rack at least 3 hours before slicing to let filling gel and hold its shape.
Garnish slices with fresh basil leaves if desired.
Great with vanilla ice cream or coconut whip.