Step 1

In a large bowl, combine the rhubarb, strawberries, sugar and cornstarch. Mix well. The mixture will start to turn thick and syrupy as it is stirred.

Step 2

Roll out the pie crust and place in a 9-inch pie plate, trimming and fluting the edges.

Step 3

Pour the strawberry/rhubarb mixture evenly in the crust.

Step 4

In a small bowl, combine the flour and brown sugar.

Step 5

Add the butter, and using a pastry cutter or two knives, cut in the butter to the flour/sugar mixture until it has the consistency of coarse crumbs.

Step 6

Sprinkle the streusel topping evenly over the top of the pie (but not covering the edges of the pie crust).

Step 7

Place the pie on a rimmed baking sheet (in case any of the filling bubbles out), and bake at 375 degrees for 50-55 minutes (see note for time edit - over the years, I've started baking this pie for 75-90 minutes so it's fully set up and not runny), until the streusel is golden and the filling is bubbling and hot. Cover the pie crust edges halfway with foil or a pie crust shield to prevent over-browning, if needed.

Step 8

Let the pie cool completely before cutting (the filling will thicken as it cools). Serve with a scoop of vanilla ice cream or sweetened, whipped cream, if desired!