Tangy gooseberry pie with a sweet, tart filling in a flaky crust is a charming, old-fashioned family dessert. This rare, heritage fruit pie is a treasure of American regional baking.
Preheat your oven to 400°F (205°C) with a rack in the lower third position for even bottom crust baking.
To make the pie pastry, cut cold unsalted butter into the flour and salt until the mixture resembles coarse crumbs; drizzle in ice water, mixing gently just until the dough comes together—avoid overworking.
Divide dough in half, shape into discs, wrap, and chill for at least 30 minutes to relax the gluten and ensure flakiness.
In a large bowl, combine gooseberries, sugar, cornstarch, lemon zest, and a pinch of salt; toss gently and let stand 10 minutes for the juices to start releasing.
Roll out the first dough disc and fit it into a 9-inch pie plate, trimming excess; pour in the gooseberry mixture, distributing evenly.
Roll the second disc and cover the filling. Trim, seal, and crimp edges. Cut several small vents for steam release. Brush the top with beaten egg for a golden finish.
Bake the pie on the lower oven rack for 20 minutes, then reduce heat to 350°F (175°C) and bake another 35-40 minutes until the crust is deep golden and the filling bubbles.
Cool on a rack for at least 2 hours to set the filling before slicing. Serve at room temperature for best flavor and texture.