Mix sugar, cornstarch, and salt in large microwave-safe bowl. Mix in water and rhubarb. Microwave on high, stirring occasionally, for about six minutes or until the rhubarb is tender and liquid has thickened. Cool to room temperature, about 30 minutes.
Preheat oven to 425°.
Roll refrigerated pie dough out to a 12-inch circle. Place dough in a pie pan and flute edge as desired.
Refrigerate for 30 minutes.
To make Streusel Topping: In a medium bowl combine flour, oats, brown sugar, cinnamon, and salt. Add butter and mix until mixture is crumbly.
Fold strawberries, orange zest, and food coloring in to cooled rhubarb mixture. Spread the filling evenly in the unbaked pie crust. Top with streusel topping.
Place pie on baking sheet and bake for 15 minutes. Reduce oven temperature to 375° and continue to bake for 15-20 minutes, until the pie is golden and the juices are bubbling. (Cover with foil if streusel is getting too brown.)
Cool completely before serving.