If using frozen rhubarb and/or strawberries, thaw before using.
Combine the sugar, cornstarch, lemon rind, nutmeg, rhubarb, strawberries and lemon juice, Let stand 20 min.
Fit one of the piecrust into a 9” pieplate, fold edges under, and crimp.
Spoon strawberry-rhubarb mixture int piecrust; dot with butter.
Roll remaining piecrust to an 1/8-inch thickness; cut into 1/2-inch strips. Arrange in a lattice design over filling. Sprinkle with 2 teaspoons sugar.
Bake at 425° for 15 minutes; reduce heat to 350°, and bake 30 more minutes or until crust browns.