Mix flour, salt, sugar; cut in butter, add ice water. Form two discs, chill 1 hour.
Toss blueberries with sugar, cornstarch, lemon juice, zest, cinnamon, salt. Taste and adjust the sweetness.
Roll one disc, fit into white ceramic pie dish. Add filling, dot with butter.
Top with second crust or lattice, brush with egg wash, sprinkle sugar. Bake at 375°F 50–60 minutes.
Cool 2 hours, serve with blueberries, ice cream, coffee.