01 - Whisk together flour, salt, and sugar (if using) in a large bowl. Add cold butter cubes and work into flour with pastry cutter or fingertips until mixture resembles coarse crumbs with pea-sized pieces. Gradually add ice water starting with 1/4 cup, mixing gently until dough just comes together. Divide dough in half, flatten into disks, wrap in plastic, and chill for at least 1 hour.
02 - Roll one chilled disk on lightly floured surface into rectangle about 1/8 inch thick. Cut at least 6 even strips using ruler and knife or pizza cutter, approximately 12 inches long and 1/2 inch wide.
03 - Lay three strips side by side with ends pressed together. Begin regular braid by crossing right strip over middle, then left over new middle. After one set, start fishtail: take outermost right strip to center, then outermost left to center, always pulling from outside. Continue until complete and press ends together. Repeat for additional braids as needed to cover pie edge.
04 - Trim excess dough from filled pie. Brush edge lightly with water to help braid adhere. Gently lift and shape braid(s) around pie rim, pressing lightly to secure. Brush braid with egg wash for golden shine.
05 - For filled pies baking longer, add braid before final baking. For pre-baked shells, chill crust with braid for 15 minutes, then bake at 375°F for 12-15 minutes until golden brown.