Mix together strawberries, rhubarb, sugar, flour, and egg.
Place a pie crust in a prepared 9-inch glass pie plate. Sprinkle lightly with sugar to prevent sogginess.
Add strawberry-rhubarb mixture. Cover with vented top pie crust.
Flute the edges to seal and cut off excess pie crust.
Bake at 425 degrees F for 20 minutes. Reduce heat to 350 degrees F and continue baking for another 30 minutes. Pie is done when crust is a light golden brown.