Preheat oven to 400°. Prep rhubarb and strawberries. Let sit on paper towels to dry.

On lightly floured surface, roll out one disk of the pastry dough into a 12″ circle to place in the center of a 9″ pie plate, pressing the dough into the bottom and sides. Let the extra dough hang over the sides. Refrigerate.

In large bowl, combine sugar and flour. Add dry rhubarb and strawberries and stir to combine.

On lightly floured surface, roll out remaining disk of pastry dough into a 10-inch circle. With a knife or pastry wheel, cut into nine 1″ wide strips.

Pour rhubarb mixture into the refrigerated pie shell. Dot with butter.

Moisten rim of pastry slightly with cold water. Arrange five pastry strips 1/2″ apart over filling. Place remaining strips across first ones at right angle, to make a lattice or weave the lattice. Press lattice ends to rim of pie and fold overhang of bottom crust over the ends of the strips. Crimp the edges to seal. Brush lattice top, but not rim lightly with milk and sprinkle with sugar.

Bake 50 minutes or until crust is golden and juice bubbles through the lattice.

Cool on wire rack. Serve warm with ice cream, if desired.