Heat the olive oil in a large Dutch oven over medium heat. Add the rhubarb, strawberries, and sugar and sauté until half of their juice is evaporated, about 10 to 15 minutes, stirring every 3 minutes or so. Remove from heat and transfer the fruit to a large bowl to cool completely.

Once cooled, stir in the flour, cinnamon, vanilla, and salt and set aside.

Pinch the mixture together with your fingertips until it resembles the texture of damp sand. Add the water, a tablespoon at a time, mixing it with a fork, until the dough just holds together when you squeeze a fistful of it in your hand. Divide the dough into two portions, one that's slightly larger than the other.

Roll out the larger portion into a circle until it is 1/8-inch thick, and transfer it to a 10-inch pie dish. Press the crust into the pan, trim off the excess leaving a 1-inch overhang, and reserve the excess dough. Scatter the bread crumbs evenly across the bottom of the pie.

Roll out the smaller portion of dough into a circle until it is 1/8-inch thick, and use a cookie cutter to cut shapes out of it.

Empty the filling into the pie shell, and then transfer the sheet of pastry onto the top of the pie and pinch the edges. Fold the 1-inch overhang under the edge of the crust all the way around. Brush the exposed crust with the egg wash, and place the pie in the freezer for 30 minutes.

Preheat the oven to 400 degrees Fahrenheit.

Place the pie in the oven and bake for 20 minutes, then lower the temperature to 375 degrees Fahrenheit and bake until the filling is jammy and the crust is golden, about 1 hour to 1 hour and 15  minutes. Remove from the oven and allow to cool for 1 hour before slicing and serving.