Needed: enough crust for a top and a bottom
Elberberries: probably 3 cups or more if your pie dish is extra deep.
sugar - tapioca granules - egg - lemon juice or vinegar (optional)

Place bottom crust in dish and shape to fit, leaving excess crust hanging over the edge for now. Prick crust all over with a fork - keeps it from pillowing up while baking (releases air beneath). Wash elderberries and drain thoroughly. In a large bowl, combine berries with sugar to taste (warning: they can be bitter! Be generous with the sugar, probably 1 to 1 1/2 cups). Add a handful of granulated tapioca (thickens the berry juices), probably 2-3 tablespoons. Add an egg to make the fruit creamy and thick. Add 1-2 tablespoons of lemon juice to bring out flavor of fruit.
Mix fruit, sugar, egg, tapioca, and lemon well and pile into crust (you may add a dash of vanilla).
Lay second pie crust out on counter and slice it into ribbons about 1/2 inch across. Place the largest ones at the center of the pie, and work out to the edges, weaving them together in a lattice. Pinch the crust ribbons fast to the bottom crust edge, pinch up a crust rim, and trim any excess that hangs over the edge.
Sprinkle the top with a dusting of white sugar - makes the finished pie sparkle.