Heirloom Ground Cherry Pie

From the garden

• 4 cups ripe ground cherries, husked and rinsed · about 1.5 pounds once husked, usually several pickings' worth

From the pantry

• 2½ cups all-purpose flour · for the pastry, plus a little for rolling
• 1 cup butter, very cold, cut in 1/2 inch cubes · 2 sticks, for the pastry
• ¾ cup granulated sugar · plus 1 tablespoon held back for the top
• 3 tbsp cornstarch · ripe husk fruit runs juicy, so do not cut this back
• 1 lemon, zested, then juiced
• ¾ tsp ground ginger
• 1 tsp vanilla extract
• 1 egg, beaten with a splash of water · for the wash
• ¾ tsp salt · half for the pastry, half for the filling

1. Sort the fruit first and keep only berries that came out of a papery tan husk golden and soft. Firm green ground cherries are unripe and mildly toxic, like the leaves and stems, so leave those on a windowsill to finish; the husks themselves are inedible and all come off.
2. Rub the cold butter into the flour and half the salt until the pieces run from oat flakes down to peas, then sprinkle in 6 to 8 tablespoons of ice water, tossing, until the dough holds when squeezed.
3. Divide the dough in two with one piece slightly larger, press each into a disk, wrap, and chill at least 1 hour. Rested pastry rolls without fighting back and shrinks far less in the oven.
4. Toss the ground cherries with the sugar, cornstarch, ginger, vanilla, lemon zest and juice, and the remaining salt. Let the bowl stand 15 minutes while the oven heats to 425°F with a rack and a sheet pan low down.
5. Roll the larger disk to a 12 inch round, line a 9 inch pie plate, and tip in the fruit with every drop of syrup from the bowl. Roll the second disk over the top, trim to a 1 inch overhang, tuck it under, and crimp.
6. Cut four wide vents, brush the top with the egg wash, and scatter over the reserved tablespoon of sugar. Bake on the hot sheet pan 20 minutes at 425°F, then 35–40 minutes at 375°F, until the crust is deep gold and thick juice bubbles slowly at the vents.
7. Cool on a rack at least 3 hours, longer if the kitchen allows. These berries carry a great deal of juice, and a warm pie runs off the server while a properly cooled one slices clean.