FOR THE FILLING
2 cups rhubarb in one-inch pieces, about one pound
3 cups strawberry halves
1 cup sugar
3 tablespoons ”minute” tapioca
3 tablespoons unsalted butter
If rhubarb is thick, peel it. Combine rhubarb and strawberries in a bowl. Mix sugar and tapioca together and fold gently into the strawberries and rhubarb. Allow to macerate for 15 minutes.
Preheat oven to 425.
Spoon fruit into pastry shell and dot with butter. Roll out remaining pastry, cut into strips three-quarters of an inch wide and weave a lattice to cover the pie. You can simply lay the strips on top in criss-cross fashion if weaving is not one of your skills. Seal, trim and crimp the edges. Brush the lattice with milk and sprinkle with a bit of sugar.
Bake in preheated oven for 15 minutes. Lower heat to 350 degrees and bake 40 minutes longer, until pastry has browned and filling begins to bubble. Let pie cool completely before serving, at least 3 hours and up to overnight to set the filling.