Wash the gooseberries and remove tops and tails.

Make the pie filling by mixing the prepared gooseberries, sugar, salt and tapioca flour (or regular flour). Don't add the butter yet. Set aside.

Mix the flour, sugar, and salt.  Dice the butter up very finely, or grate it while frozen.  Cut the butter into the flour, until it looks like sand.

Add ice water slowly, and stir until it's just incorporated.  Bring the dough together into one disk, and then cut it in half to make two.

Roll each out into a large disk that's about 1/8 to 1/4 inch thick to make your two pie rounds.

Place one on the bottom of your pie pan and then fill with the gooseberry pie filling mix.  Place 1 to 2 tbsp butter on top of the filling, and then top with the other half of the pie crust.

Crimp edges and prepare to bake.  (For a prettier pie, brush with milk or egg white, and then sprinkle sugar on the top before baking.)

Preheat the oven to 425 F (220 C).  Bake the pie for 15 minutes, then turn the oven down to 375 (190 C) and bake for an additional 35 to 40 minutes, until the filling is bubbling hot and the top is golden brown.

Cool the pie completely before serving so the fruit can set up.