3 cups chopped fresh or frozen rhubarb (1-inch pieces), thawed and drained
1 cup fresh or frozen unsweetened raspberries
Pastry for a double-crust pie (9 inches)
2 teaspoons butter
In a large bowl, combine the sugar, tapioca, salt and cinnamon. Add rhubarb and raspberries; toss gently. Let stand for 20 minutes.
Line a 9-in. pie plate with bottom pastry; trim pastry even with edge. Pour filling into crust; dot with butter. Roll out remaining pastry; make a lattice crust. Trim, seal and flute edges.
Bake at 400° for 30 minutes. Remove foil; bake 5-10 minutes longer or until pastry is golden brown and filling is bubbly. Cover edges with foil during the last 15 minutes to prevent overbrowning if necessary.
If using frozen rhubarb, measure rhubarb while still frozen, then thaw completely. Drain in a colander, but do not press liquid out. If using frozen raspberries, use without thawing to avoid discoloring the batter.